Download Engineering Energy Conversion Devices

First 60-Day Public Review Draft
November 2015
1
High School Three Course Model –
2
Physics in the Universe: Integrating Physics and Earth & Space Science
3
4
Introduction
Physical processes govern everything in the Universe. Geoscientists require a
5
strong background in the laws of physics in order to interpret processes that shape the
6
Earth system. Forces of moving water push tiny particles of sand along beds of rivers,
7
sometimes hard enough that they collide with the rocks with such force that a piece of
8
the river bed breaks off. Over time, the Grand Canyon forms. Gravity pulls constantly on
9
rocks at the surface of the Earth, and sometimes the frictional forces resisting
10
movement falter. A landslide crashes down a canyon, destroying everything in its path.
11
The nuclei of atoms thousands of miles below the surface that have remained stable for
12
millions of years spontaneously explode apart, releasing massive amounts of energy
13
and heating up the surrounding rock. A geyser of hot steam erupts in California,
14
releasing some of this excess heat to the surface. In each case, an Earth or space
15
scientist is studying the physics of the situation, perhaps using a computer model to fast
16
forward millions of years of energy transfer to explain what we see on Earth today.
17
Alongside this scientist is a team of engineers, looking hoping to use this understanding
18
to design and test solutions to many of society’s problems from natural hazards to
19
global warming or to minimize our impact on the natural world.
20
Physics teachers may not have a strong Earth science background. While it is
21
true that there may be details and historical background that are new, the physical
22
processes are not. The laws of physics are universal. In fact, Earth and space science
23
applications are excellent motivations to the study of physical laws. A classic example is
24
waves, a topic with such universal importance that CA NGSS devotes an entire set of
25
DCIs in physical science to them. With such significance, it seems unfortunate that the
26
most common classroom application of them is a string held between two people. While
27
it is indeed elegant that such a simple demo can capture such a rich process, it is hard
28
to claim that this demonstration is truly exciting or invokes great curiosity. Earthquakes,
First 60-Day Public Review Draft
November 2015
29
however, are all about waves and students are filled with questions motivated by
30
personal relevance in California. Earthquakes can be visualized with real time data
31
downloaded from around the world, or with accelerometers built into nearly every cell
32
phone. Frequency, period, and amplitude are all there on a seismogram, ready to be
33
interpreted. Earth science can be a door into physics.
34
Even a physics teacher that is enthusiastic about this integration in principle may
35
still feel apprehensive about teaching a course that deals with a discipline they may
36
never have studied. Research on self-efficacy shows that a teacher that is not confident
37
will not teach as effectively, often reverting to tasks with low cognitive demand rather
38
than the rich three-dimensional learning expected by CA NGSS. Districts should be
39
mindful and be sure to allocate resources to professional development and collaborative
40
planning time so that teachers can learn from one another. No matter what resources
41
are allocated, teachers will still have to choose how to react to the change. Science
42
teachers, as a general rule, became science teachers because they love learning about
43
science. Teachers can try to approach this course with an appreciation for the
44
opportunity to learn about a new science alongside students. They can be beacons of
45
curiosity and inquiry in their classrooms. A teacher asking questions and seeking
46
answers is a much better role model than a teacher that appears to know everything.
47
This section of the Science Framework is meant to be a guide for how to
48
approach the teaching of a high school course that integrates physics and Earth and
49
space sciences and is not meant to be an exhaustive list of what can be taught or how it
50
should be taught. Teachers are free to address the PEs with applications and
51
phenomena from ESS and PS that interest them most, and can present these lessons
52
in the order that makes the most logical and logistical sense to them.
53
Care was taken in designing this course so that it does not require a specific
54
sequence with respect to the biology or chemistry courses and should be useful in
55
helping course design regardless of sequence. As such, it lacks some of the rich
56
interdisciplinary connections that are possible. As schools and districts adopt a specific
57
sequence, they can take advantage of links to previous courses by making connections
58
to this prior knowledge.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 2 of 106
First 60-Day Public Review Draft
59
60
November 2015
Motivation for the Sequence of This Course
There are many possible storylines, though a rich integration of ESS applications
61
does impact the sequence so that it probably needs to differ from the sequence
62
teachers would use for teaching core ideas from physical science alone. The benefit is
63
that the ESS concepts can help make the physical science concepts relevant and
64
exciting.
65
The decision for the focus and sequence of this model framework course is
66
based on a specific storyline surrounding renewable energy. Both physical science
67
(PS) and ESS DCIs emphasize how discoveries in their discipline influence society, but
68
the two differ in which aspects of society they focus upon. Physical science emphasizes
69
society’s use of technology while Earth and space science emphasizes humanity’s
70
impact on natural systems and the other way around (issues defined in California’s
71
Environmental Principles and Concepts, or EP&Cs). A major emphasis in the first
72
several instructional segments of this course is one societally relevant topic where these
73
two disciplinary focuses intersect: electricity production. The main engineering design
74
challenges relate to designing, building, evaluating, and refining systems for electricity
75
generation and considering the environmental impacts of each method on the different
76
components of Earth’s systems. The theme is not all-encompassing, as many of the
77
PE’s pertain to core ideas that are disjoint from renewable energy.
78
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 3 of 106
First 60-Day Public Review Draft
November 2015
79
80
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 4 of 106
First 60-Day Public Review Draft
November 2015
81
Model Course Mapping for Physics in the Universe
82
83
Teachers and educators are strongly advised to review the introductory chapters of this
84
framework, including the chapter on Instructional Strategies.
85
86
A primary goal of this section is to provide an example of how to bundle the PEs
87
into related groups that can form the basis for the instructional segments. There are six
88
instructional segments in this course, so each would correspond to a bit more than one
89
month of classroom instruction in a traditional school calendar year, though the
90
instructional segments are not equal in duration.
91
Within this document, an explicit description is provided of how each PE in an
92
instructional segment relates to one another. Ensuring that the scientific concepts
93
smoothly transition from one to the next emphasizes the fact that these topics build on
94
one another.
95
96
Table 1. Summary table for a model course integrating physics and Earth & space science in High School
Instructional segment 1:
Forces and Motion
97
Performance Expectations Addressed
HS-PS2-1, HS-PS2-2, HS-PS2-3*, HS-ETS1-1, HS-ETS1-4
Highlighted SEP
Highlighted DCI
Highlighted CCC
PS2.A – Forces and
 Analyzing and
 Cause and
Motion
interpreting data
effect
ETS1.A – Defining and
 Mathematics and
 Systems, and
Delimiting Engineering
computational
system models
Problems
thinking
 Developing and using ETS1.B – Developing
Possible Solutions
models
 Planning and carrying
out investigations
 Defining problems
 Designing solutions
Summary of DCI
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 5 of 106
First 60-Day Public Review Draft
November 2015
Force is equal the product of mass and acceleration. In a closed system,
the total momentum is constant.
Instructional segment 2:
Forces at a distance
98
99
Performance Expectations Addressed
HS-PS2-4, HS-PS2-5, HS-PS2-6*, HS- ETS1-1
Highlighted SEP
Highlighted DCI
Highlighted CCC
 Developing and using PS2.B – Types of
 Cause and
Interaction
models
effect
ETS1.A – Defining and
 Mathematics and
 Structure and
Delimiting Engineering
computational
function
Problems
thinking
 Planning and carrying
out investigations
 Analyzing and
interpreting data
 Constructing
explanations (for
science) and
designing solutions
(for engineering)
 Obtaining, evaluating,
and communicating
information
Summary of DCI
The inverse square law applies to gravity and electromagnetic interactions.
Flowing electrons produce a magnetic field, and spinning magnets cause
electric currents to flow.
100
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 6 of 106
First 60-Day Public Review Draft
November 2015
Instructional segment 3:
Energy conversion
101
Performance Expectations Addressed
HS-PS1-8, HS-PS3-2, HS-PS3-5, HS-PS3-3*, HS-ETS1-2
Highlighted SEP
Highlighted DCI
Highlighted CCC
PS3.D – Energy in
 Developing and
 Energy and
Chemical
Processes
and
using models
matter: Flows,
Everyday Life
cycles and
PS3.A – Definitions of
conservation
Energy
PS3.B – Conservation of
Energy and Energy
Transfer
PS3.C – Relationship
Between Energy and
Forces
Summary of DCI
Energy exists in a variety of forms. Humans depend on the ability to convert
these forms from one in our bodies and our technologies.
Instructional segment 4:
Nuclear processes
102
Performance Expectations addressed
HS-PS1-8, HS-ESS1-5, HS-ESS1-6, HS-ESS2-1
Highlighted SEP
Highlighted DCI
Highlighted CCC
 Developing and using PS1.C – Nuclear
 Energy &
Processes
models
matter
PS1.C – The History of
 Analyzing and
 Stability &
Planet Earth
interpreting data
change
ESS2.B – Plate Tectonics
and Large-Scale System
Interactions
Summary of DCI
Changes to atomic nuclei release energy and change atoms from one
element to another.
103
104
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 7 of 106
First 60-Day Public Review Draft
November 2015
Instructional segment 5:
Waves and Electromagnetic Radiation
Performance Expectations addressed
HS-PS4-1, HS-PS4-3, HS-PS4-4, HS-PS4-5*, HS-PS4-2, HS- ETS1-1
Highlighted SEP
Highlighted DCI
Highlighted CCC
PS4.A – Wave Properties
 Asking questions
 Energy &
PS4.B
–
Electromagnetic
matter
 Using mathematics
Radiation
and computational
 Cause &
PS4.C – Information
thinking
effect
Technologies and
 Engaging in
 Systems &
Instrumentation
argument from
system
PS3.D – Energy in
evidence
models
ETS1.A
–
Defining
and
 Obtaining, evaluating
 Stability and
Delimiting Engineering
and communicating
change
Problems
information
Summary of DCI
Electromagnetic radiation has many applications, and can be modeled as a
wave of changing electric and magnetic fields or as particles called photons.
Instructional segment 6:
Stars and the Origins of the
Universe
105
106
Performance Expectations addressed
HS-ESS1-1, HS-ESS1-2, HS-ESS1-3
Highlighted SEP
Highlighted DCI
Highlighted CCC
 Developing and using ESS1.A – The Universe
 Energy &
and Its Stars
models
Matter
PS1.C
–
Nuclear
 Constructing
 Patterns
processes
explanations
 Cause &
effect
 Scale,
proportion,
& quantity
Summary of DCI
The light from stars tells us about their composition and how they are
moving away from us.
107
108
109
110
111
112
113
114
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 8 of 106
First 60-Day Public Review Draft
November 2015
115
116
Instructional segment-1 Forces and Motion
Physics - Instructional segment 1: Forces and Motion
Guiding Questions:

How can Newton’s Laws be used to explain how and why things move?

How can mathematical models of Newton’s Laws be used to test and
improve engineering designs?
Science and Engineering Practices:

Analyzing and interpreting data

Mathematics and computational thinking

Developing and using models

Planning and carrying out investigations

Defining problems

Designing solutions
Crosscutting concepts:

Cause and effect: Mechanism and explanation

Systems and system models, structure and function
Students who demonstrate understanding can:
HS-PS2-1. Analyze data to support the claim that Newton’s second law of
motion describes the mathematical relationship among the net
force on a macroscopic object, its mass, and its acceleration.
[Clarification Statement: Examples of data could include tables or
graphs of position or velocity as a function of time for objects subject to
a net unbalanced force, such as a falling object, an object rolling down a
ramp, or a moving object being pulled by a constant force.] [Assessment
Boundary: Assessment is limited to one-dimensional motion and to
macroscopic objects moving at non-relativistic speeds.]
HS-PS2-2. Use mathematical representations to support the claim that the
total momentum of a system of objects is conserved when there is
no net force on the system. [Clarification Statement: Emphasis is on
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 9 of 106
First 60-Day Public Review Draft
November 2015
the quantitative conservation of momentum in interactions and the
qualitative meaning of this principle.] [Assessment Boundary:
Assessment is limited to systems of two macroscopic bodies moving in
one dimension.]
HS-PS2-3. Apply scientific and engineering ideas to design, evaluate, and
refine a device that minimizes the force on a macroscopic object
during a collision.* [Clarification Statement: Examples of evaluation
and refinement could include determining the success of the device at
protecting an object from damage and modifying the design to improve
it. Examples of a device could include a football helmet or a parachute.]
[Assessment Boundary: Assessment is limited to qualitative evaluations
and/or algebraic manipulations.]
HS-ETS1-1. Analyze a major global challenge to specify qualitative and
quantitative criteria and constraints for solutions that account for
societal needs and wants.
HS-ETS1-4. Use a computer simulation to model the impact of proposed
solutions to a complex real-world problem with numerous criteria
and constraints on interactions within and between systems
relevant to the problem.
* This performance expectation integrates traditional science content with
engineering through a practice or disciplinary core idea.
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
According to the NGSS storyline,
The Performance Expectations associated with the topic Forces and
Interactions supports students’ understanding of ideas related to why
some objects will keep moving, why objects fall to the ground, and why
some materials are attracted to each other while others are not. Students
should be able to answer the question, “How can one explain and predict
interactions between objects and within systems of objects?” The
disciplinary core idea expressed in the Framework for PS2 is broken down
into the sub ideas of Forces and Motion and Types of Interactions. The
performance expectations in PS2 focus on students building
understanding of forces and interactions and Newton’s Second Law.
Students also develop understanding that the total momentum of a system
of objects is conserved when there is no net force on the system. Students
are able to use Newton’s Law of Gravitation and Coulomb’s Law to
describe and predict the gravitational and electrostatic forces between
objects. Students are able to apply scientific and engineering ideas to
design, evaluate, and refine a device that minimizes the force on a
macroscopic object during a collision. The crosscutting concepts of
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 10 of 106
First 60-Day Public Review Draft
136
137
138
139
140
141
142
143
144
145
November 2015
patterns, cause and effect, and systems and system models are called out
as organizing concepts for these disciplinary core ideas. In the PS2
performance expectations, students are expected to demonstrate
proficiency in planning and conducting investigations, analyzing data and
using math to support claims, and applying scientific ideas to solve design
problems; and to use these practices to demonstrate understanding of the
core ideas. (NGSS Lead States 2013)
Background for Teachers and Instructional Suggestions
What does a mountain peak have in common with a pickup truck? If the vehicle
146
is involved in a crash, its hood will crumple and bend under the force of the collision.
147
Mountain ranges, like the Himalayas, are shortened and pushed upwards just like the
148
hood of a crashed car. Even though the two processes occur at very different scales,
149
they are both governed by Newton’s Laws.
150
151
152
Figure 1. Mountains and car crashes involve collisions whose movement and forces
153
can be modeled in computer simulations (bottom). (Insurance Institute for Highway
154
Safety 2011; Cinedoku Vorarlberg 2009; Willett 1999; Structural Tech 2006)
155
Engineers and scientists can apply Newton’s Laws mathematically or with
156
computational models to predict the motion of objects. These calculations (including
157
those depicted in the bottom panels of Figure 1) enable them to do things like build
158
safer automobiles and provide more reliable forecasts of earthquake hazard.
159
Predictions applying Newton’s Laws have been shown to be accurate for all objects
160
except those at certain extreme scales (such as objects traveling near the speed of
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 11 of 106
First 60-Day Public Review Draft
November 2015
161
light and extremely small particles such as atoms or subatomic particles that obey the
162
principles of quantum mechanics). Newton’s Laws provide a basis for understanding
163
forces and motion, and therefore serve as a foundation for a study of physics. Newton’s
164
first law, the law of inertia, states that every object in a state of uniform motion tends to
165
remain in that state of motion unless it is subjected to an unbalanced external force.
166
Newton’s second law, the definition of force, states the relationship between the applied
167
force, F, an object's mass m, and its acceleration a, expressed as F = ma. Finally,
168
Newton’s third law, the law of reciprocity, states that when one body exerts a force on a
169
second body, the second body simultaneously exerts a force equal in magnitude and
170
opposite in direction on the first body, often described as “for every action, there is an
171
equal and opposite reaction”.
172
173
174
Figure 2. Students can analyze many devices that minimize the force on a macroscopic
175
object during a collision. (Clemson University Vehicular Electronics Laboratory 2015;
176
Grabianowski 2008; Chandigarh Traffic Police 2015; VectorStock 2015)
177
Like practicing engineers, this instructional segment is organized around a
178
design challenge where students design a device that “minimizes the force on a
179
macroscopic object during a collision” (HS-PS2-3). For example, air bags, car crumple
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 12 of 106
First 60-Day Public Review Draft
November 2015
180
zones, helmets, parachutes, and padded catcher’s mitts (Figure 2). reduce the potential
181
for injury by decreasing the force necessary to bring objects to a halt by increasing the
182
time over which such forces are applied. In the process, students are demonstrating
183
competence with HS-ETS1-1, which involves starting by considering a complex
184
problem, such as automobile collisions, or sports injuries, and specifying qualitative and
185
quantitative criteria and constraints for solutions. With teacher guidance the students
186
can then break down the problem into smaller, more manageable problems that can be
187
solved through engineering (HS-ETS1-2). The students should be encouraged to
188
generate multiple solutions, which they would then evaluate based on prioritized criteria
189
and trade-offs, taking into account cost, safety, and reliability as well as social, cultural,
190
and environmental impacts (HS-ETS1-3). Students can experience additional phases of
191
the engineering design process by building and testing a model of their most promising
192
idea and then modifying it based on the results of the tests. Testing can include
193
computer simulations that model how such solutions would function under different
194
conditions (HS-ETS1-4). Students performed a similar design challenge at the middle
195
grade level in which they applied Newton’s third law to design a solution to a problem
196
involving the collision of two objects (MS-PS2-1). The high school ETS standards also
197
have greater emphasis on quantifying trade-offs and prioritizing criteria (HS-ETS1-3), so
198
this design challenge might include added constraints about material costs. Middle
199
grade ETS standards heavily emphasize iterative testing and may lend themselves to
200
an emphasis on trial and error. The high school challenge implies a more detailed
201
understanding and calculation of forces. Throughout the process, the emphasis is on
202
explaining design choices and revisions in terms of these physics concepts. The
203
design challenge therefore serves as a culmination of the instructional segment, but
204
students should be introduced to the challenge at the beginning of the instructional
205
segment and the specific phenomenon investigated throughout the instructional
206
segment should be chosen to build towards the specific design challenge.
207
In order to successfully complete the design challenge, students need to develop
208
the mathematical tools to relate forces and motion. At the middle grade level, students
209
analyzed data to identify a relationship between force, mass, and motion (MS-PS2-2).
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 13 of 106
First 60-Day Public Review Draft
November 2015
210
Now students employ mathematical thinking to apply the simple mathematical model
211
formulated in Newton’s second law (F=ma, Force = mass x acceleration). They analyze
212
and interpret tables or graphs of position as a function of time, or velocity as a function
213
of a time for objects subjected to a constant, net unbalanced force and compare their
214
observations to predictions from the mathematical model (HS-PS2-1). Given the force
215
and the mass, students learn to calculate the acceleration of an object. Given the mass
216
and the acceleration, students should be able to calculate the net force on the object.
217
Accordingly, students should be able to analyze simple free-body diagrams to calculate
218
the net forces on known masses, and subsequently determine their acceleration. In
219
each of these cases, the clarification statement for HS-PS2-1 states that students
220
should be examining situations where the force remains constant during the interaction.
221
Gravity is the most consistent way to apply a constant force, so the most consistent
222
results will come from analyzing objects moving down ramps or falling. Computer
223
simulations and digital video analysis tools generate graphs of position vs. time, speed
224
vs. time and acceleration vs. time, providing an opportunity to visualize, analyze and
225
model motion.
226
Newton’s second law can also be used to test the strength of different materials
227
for a design challenge. A satellite must withstand vibrations from a rocket launch, a
228
hospital must withstand earthquake shaking, and a child’s toy must be able to withstand
229
being sat upon by a toddler. In many of these cases, it is not practical to do iterative
230
testing on the actual objects (they cannot build various trials of a hospital and have each
231
of them fall down –each one takes years and cost millions of dollars to complete).
232
Instead, engineers do calculations to test their designs before investing the time and
233
materials of actually building a prototype. In the classroom, students could determine
234
the maximum force a toothpick can withstand before it snaps or a toilet paper tube
235
before it buckles. They do this by placing heavy objects on top of the test material and
236
measuring the amount of mass that causes the material to break. Since the
237
acceleration of gravity is constant, the force can be calculated using the mathematical
238
model W = mg (a special case of F = ma where W is the force of the object’s weight, m
239
is mass, and g is the constant of gravitational acceleration). By comparing this force to
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 14 of 106
First 60-Day Public Review Draft
November 2015
240
calculations of the expected force on impact during their design challenge, they can
241
make informed decisions about materials. Engineers perform similar calculations to
242
provide evidence that their design will withstand the expected forces. Often, computer
243
simulations like Figure 1 are used for these calculations.
244
Newton’s second law is written from the perspective of an isolated object with a
245
net external force acting upon it. With a system of two or more objects interacting (such
246
as during a collision), Newton’s third law also becomes important for describing the
247
forces between the objects. Students made qualitative explanations of the exchange of
248
energy during collisions at the middle grade level (MS-PS3-5), but now students use a
249
mathematical model to describe a different aspect of the collision. A consequence of
250
Newton’s laws is that a quantity called linear momentum stays constant within a system
251
that has no net external forces acting upon it. Momentum is expressed as mass times
252
velocity and conservation of momentum means that the momentum lost by one object in
253
a two body system must equal the momentum gained by the other object. Conservation
254
of momentum can be applied to collisions and students can predict how much the
255
velocity of objects with known masses will change when they collide. Comparing
256
predictions to measurements provides evidence to support the claim that momentum is
257
conserved during a collision (HS-PS2-2).
258
The assessment boundaries for HS-PS2-1 and HS-PS2-2 are limited to one-
259
dimensional systems with constant forces. Most everyday interactions, however, are
260
more complicated and involve complex, three-dimensional systems in which forces and
261
accelerations change. Thus, the motion of such things as a swinging trapeze artist, the
262
crushing of a car door during a side impact, or the ground shaking during an earthquake
263
can be broken down and analyzed qualitatively in terms of the three-dimensional forces
264
acting on the objects at each moment during the motion. Computational models employ
265
this exact strategy, using Newton’s laws to calculate changes in motion over a series of
266
short, successive time increments.
267
There are a number of observations based on everyday experience that seem to
268
contradict Newton’s laws and the law of conservation of momentum that can be derived
269
from them. For example, a rolling basketball will come to a stop unless given an
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 15 of 106
First 60-Day Public Review Draft
November 2015
270
additional push, while the momentum of a basketball reverses simply by bouncing off a
271
backboard in the absence of a visible force. Similarly, a runner races forward without
272
the earth moving backwards. In each of these situations, there are forces or parameters
273
that students often neglect in their intuition (such as friction or elastic forces). With
274
experience, they can begin to recognize evidence of these processes so that they can
275
slowly replace their preconceptions of how the world works with one that truly
276
incorporates the physics of Newton’s laws.
Snapshot of a Physics Lesson: Forces and Motion in Geology
Mr. H runs an efficient technology-enhanced classroom where he is helping students
become self-starters on engaging individual projects. After a few weeks investigating
Newton’s laws through laboratory data analysis (HS-PS2-1), direct instruction, guided
practice, and homework problem sets, Mr. H. wants his students to be able to relate
them to Earth processes.
As Mr. H.’s students enter the room, they open the class website on their mobile
devices and find today’s agenda. Each group of three students is assigned to
investigate and characterize one of the following land and sea-floor features with a
virtual globe, map and geographical information program such as Google Earth:
trenches (Mariana, Aleutian, Puerto Rico, Japan), oceanic ridges (Mid-Atlantic, East
Pacific, Nazca, Mid-Indian), seamounts (Loihi, Davidson, Tamu Massif, Banua Wuhu),
mountain ranges (Himalaya, Sierra Nevada, Rocky Mountains, Alps), valleys (California
Central Valley, Ethiopian Rift, Yosemite Valley, Rhone), or plateaus (Kukenan Tepui,
Monte Roraima, Table Mountain, Auyantepui). As the opening bell rings, students are
already actively searching their geomorphic features. Mr. H. uses remote desktop to
freeze their devices so he can clarify the instructions printed on the agenda webpage.
Each team is to develop a tour-guide script that one of their members will read as they
introduce their geomorphic feature to the class. Each group is to create a narrated
animated tour in which they provide voiceovers, and descriptive pop-up balloons, as
they “fly” their audience around the globe in a video-like experience. Each animated “flyby” or “float-by” tour must include a description of the constructive forces (such as
volcanism and tectonic movements) and destructive mechanisms (such as weathering,
landslides, and coastal erosion) that have shaped their feature (HS-ESS2-1). Students
work throughout the period, integrating their knowledge of plate motions and surface
processes with the features they observe. Students are required to make strategic use
of digital media (e.g., textual, graphical, audio, visual, and interactive elements) in their
presentations to enhance understanding of findings, reasoning, and evidence and to
add interest, thereby meeting CCSS SL.11-12.
The following day, students proudly present their fly-by videos, providing the class with
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 16 of 106
First 60-Day Public Review Draft
November 2015
an introduction to key oceanic and continental geomorphic features. Following the video
presentations, Mr. H. asks students to describe how Newton’s Laws helps explain the
formation of such features. Students type their responses into an online form that allows
Mr. H to monitor their thinking in real-time. It soon becomes clear that although his
students seem to have a good grasp of Newton’s laws as measured by a traditional
assessment, and although they seem to have a good understanding of key geomorphic
features, they seem to be unable to apply Newton’s Laws to explain the formation of
such features.
Mr. H. proceeds with an interactive lecture on the concept of geological stress
(pressure), the ratio of force per unit area. Although pressure is easy to conceptualize
and measure using the simple, homogenous, discrete objects commonly used in
physics investigations, it is much more difficult to
understand when discussing complex, heterogeneous,
continuous objects such as the Earth’s crust. To help
students visualize the application of Newton’s Laws in
geological systems, Mr. H. presents a squeeze box with a
screw mechanism (Figure x). Layers of dark and light sand
are placed in alternating horizontal layers in the box and
pressure is applied with a screw mechanism. As the crank
turns, layers deform, simulating geological folding and
mountain building. Unlike other physics problems the
students have considered with rigid objects, the sand is
clearly not rigid. Scientists often break down complex
(Exploratorium Teacher
problems like this into much smaller pieces, where the
Institute
smaller pieces each behave like a rigid body. Mr. H shows
an example where scientists use this sort of computational 2000)/activities/The_Squeez
e_Box.pdf
thinking using computer simulations called ‘discrete
element analysis.’
Image Credit: Handy 2006
Mr. H asks students to work in pairs to label the forces acting on a small section of sand
near the middle of the model. Students upload photos of their diagrams to the class
webpage so that everyone can see their peers’ work. Mr. H selects two student
diagrams to show side-by-side and asks the class to identify the differences. Most of the
students had correctly identified the force related to the crank pushing on one side, but
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 17 of 106
First 60-Day Public Review Draft
November 2015
a substantial fraction of them forget to include the force of the opposing wall. Mr. H asks
students to consider the vector sum of the forces to make sure it points in the same
direction as the change in motion.
Image Credit: M. d’Alessio
Mr. H next asks students how Newton’s second law (F=ma) applies to this situation
using the online student response form. This time, many students mention that force
(applied through the screw) causes the mass of the individual particles (sand) to
accelerate as evidenced by the movement of layers within the box. Mr. H tells the
students that there is some truth to that statement, but he disagrees that this
explanation describes most of the motion within the system. He challenges his students
to identify the evidence that he is basing his argument upon. They are confused at first,
but Mr. H walks around as teams of students discuss his statement. He asks them
leading questions, such as “how would you describe the velocity of the wall?” Each
team eventually realizes that once it started moving, the wall continued to move at a
constant velocity and was therefore not accelerating. A large fraction of the sand in the
model moves constantly but does not deform, so it too does not accelerate. At any
given time, only a small fraction of the model is accelerating. The same thing happens
in the real world. Mr. H shows observations from precise GPS measurements that
reveal most plates move at constant rates in constant directions for decades (i.e., no
acceleration). There are clearly forces being applied to the system, so how come it
doesn’t accelerate despite the constant force applied on the edges? Some students
recognize friction as being important as the grains of sand slide past one another. They
reason that friction or other forces within the system must balance the external forces.
Earth scientists studying plate tectonics consider both the driving forces that push and
pull the plates (related to gravity and convective processes in Earth’s interior) as well as
friction along the boundaries of plates (including drag along the bottom), momentum
transfer from collisions with other plates, and the forces that arise from energy
dissipation from friction within materials (often called ‘plastic deformation’). Even today,
scientists are still trying to find ways to measure or estimate the strength of these forces
to determine which ones are ‘most important’ for causing the plates to move and
deform. Beyond plate motions, plastic deformation is an important part of the energy
balance of devices that minimize force during collisions such as vehicle crumple zones
(related to HS-PS2-3).
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 18 of 106
First 60-Day Public Review Draft
November 2015
Science and engineering
practices
Disciplinary core ideas
Cross cutting concepts
Analyzing and interpreting
data
PS2.A:
Cause and effect: Mechanism
Using mathematics and
computational thinking
Newton’s second law accurately and explanation
predicts changes in the motion of
macroscopic objects.
Stability and change
Engaging in argument from
evidence
Connections to the CA CCSSM: MP. 2
Connections to CA CCSS for ELA/Literacy: SL.11-12.4, SL.11-12.5
Connection to CA ELD Standards : ELD.P1.11-12.C9-11
Connections to the CA EP & Cs: none
277
278
The design challenge described at the beginning of the instructional segment
279
tests students’ understanding of the momentum-impulse connection: FΔt=mΔv, where
280
F=force, t=time, m=mass, and v=velocity. The product of force and the time over which
281
the force is applied is known as the impulse (FΔt), and is equal to the change in
282
momentum of the object to which the force is applied (mΔv). One can decrease the
283
force necessary to bring a moving object to rest by increasing the time over which the
284
force is applied. HS-PS2-3 gives students the opportunity to design and test devices
285
that minimize the force necessary to bring moving objects to a standstill. A classic
286
activity that meets this PE is the egg-drop contest, in which students are challenged to
287
develop devices that protect raw eggs from breaking when dropped from significant
288
heights (Figure 3). This challenge employs a wide range of science and engineering
289
practices and enhance their understanding of crosscutting concepts. For example,
290
students define the problem by understanding the design objective and their material
291
constraints. They can break the mechanical problem of minimizing force down into
292
smaller, more manageable problems (HS-ETS1-2) such as finding ways to slow the
293
descent or lengthen the time of contact during the collision. Like many mechanical
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 19 of 106
First 60-Day Public Review Draft
November 2015
294
engineering tasks, they are designing an object whose structure achieves a specific
295
function. The process of optimizing solutions forces students to isolate specific cause
296
and effect relationships between components of their structure and the performance
297
result. They realize that their device operates as a system with interacting components
298
where changes in one part of their design often lead to consequences for other parts.
299
300
Figure 3. Students learn physics principles such as impulse and momentum while
301
simultaneously learning engineering design and testing principles while designing and
302
developing devices for challenges such as the classic egg-drop contest.
303
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 20 of 106
First 60-Day Public Review Draft
November 2015
304
305
Instructional segment-2 Types of Interactions (PS2.B)
Physics - Instructional segment 2: Types of Interactions (PS2.B)
Guiding Questions:

How can different objects interact when they are not even touching?

How do interactions between matter at the microscopic scale affect the
macroscopic properties of matter that we observe?

How do satellites stay in orbit?
Science and Engineering Practices:

Developing and using models

Mathematics and computational thinking

Planning and carrying out investigations

Analyzing and interpreting data

Constructing explanations (for science) and designing solutions (for
engineering)

Obtaining, evaluating, and communicating information
Crosscutting concepts:

Cause and effect: Mechanism and explanation

Structure and function

Scale, proportion, and quantity
Students who demonstrate understanding can:
HS-PS2-4 Use mathematical representations of Newton’s Law of
Gravitation and Coulomb’s Law to describe and predict the
gravitational and electrostatic forces between objects. [Clarification
Statement: Emphasis is on both quantitative and conceptual
descriptions of gravitational and electric fields.] [Assessment Boundary:
Assessment is limited to systems with two objects.]
HS-PS2-6 Communicate scientific and technical information about why the
molecular-level structure is important in the functioning of
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 21 of 106
First 60-Day Public Review Draft
November 2015
designed materials.* [Clarification Statement: Emphasis is on the
attractive and repulsive forces that determine the functioning of the
material. Examples could include why electrically conductive materials
are often made of metal, flexible but durable materials are made up of
long chained molecules, and pharmaceuticals are designed to interact
with specific receptors.] [Assessment Boundary: Assessment is limited
to provided molecular structures of specific designed materials.]
306
307
308
Background for Teachers and Instructional Suggestions
Instructional segment 1 introduces the concept of force as an influence that tends
309
to change the motion of a body or produce motion or stress within a stationary body.
310
While forces govern a wide range of interactions, the design challenge and many of the
311
simplest applications from instructional segment 1 primarily involved interactions
312
between objects that appeared to be physically touching. Instructional segment 2 builds
313
upon this foundation by examining gravity and electromagnetism, forces that can be
314
modeled as fields that span space. Despite the fact that we cannot see them, we
315
interact with these fields on a daily basis and students are already familiar with their
316
pushes and pulls.
317
At the middle grade level, students laid out a firm groundwork for studying these
318
forces. They gathered evidence that fields exist between objects and exert forces (MS-
319
PS2-5), asked questions about what causes the strength of electric and magnetic
320
forces to vary (MS-PS2-3), and determined one factor that affects the strength of the
321
gravitational force (MS-PS2-4). This high school instructional segment extends those
322
skills by providing mathematical models of these forces. Though students’ everyday
323
experience with electric forces, magnetic forces, and gravity all seem to be independent
324
of one another, these mathematical models will reveal some important connections
325
between them.
326
Science and Engineering Practices and the History of Gravity
327
Although scientists have studied gravity and electromagnetism intensely for
328
centuries, many mysteries remain concerning the nature of these forces. The CA NGSS
329
learning progression mirrors the historical development of our understanding of gravity
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 22 of 106
First 60-Day Public Review Draft
November 2015
330
and orbital motion. In 1576, Danish scientist Tycho Brahe set up the world’s most
331
sophisticated astronomical observatory of its time. He methodically investigated and
332
recorded the motion of celestial objects across the sky. Just before he died, Brahe took
333
on Johannes Kepler as a student who analyzed the data to develop a simple
334
descriptive model. Even though his model did a superb job of predicting the motion of
335
objects in the sky, it was incomplete because it could not explain the fundamental forces
336
driving the motions. In late 1600’s, Isaac Newton extended Kepler’s model by describing
337
the nature of gravitational forces. From his fundamental equations of gravity, Newton
338
was able to derive Kepler’s geometric laws and match the observations of Brahe.
339
Despite the fact that Newton’s work was revolutionary, he became so well-known
340
because his book, Principia Mathematica, did such a good job of communicating
341
information. In NGSS, elementary students mirror the work of Brahe, recognizing
342
patterns in the sky (1-ESS1-1, 5-ESS1-2). At the middle grade level, students mirror
343
the work of Kepler by making simple models that describe how galaxies and the solar
344
system are shaped (MS-ESS1-2). In high school, students add mathematical thinking
345
to their descriptive model (using Kepler’s laws, HS-ESS1-4) and then finally extend their
346
model to a full explanation with the equations of the force of gravity from Newton’s
347
model (HS-PS2-4).
348
349
350
Equations of Gravitational Force
Newton’s Law of Gravitation is a mathematical expression to describe and
351
predict the gravitational attraction between two objects. Newton’s Law is expressed as
352
F=Gm1m2/r2, where F represents the gravitational force, m1 and m2 represent the
353
masses of two interacting objects, r represents the distance (radius) between the
354
centers of mass of these two objects, and G is the universal gravitational constant.
355
356
357
358
Common Core Connection: Rearranging Formulas
The Common Core Mathematics standard MATH.HAS.CED.A.4 states that
students should be able to “rearrange formulas to highlight a quantity of interest, using
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 23 of 106
First 60-Day Public Review Draft
November 2015
359
the same reasoning as in solving equations.” Thus, given G and any three of the
360
variables, students should be able to apply basic algebra to calculate the value of the
361
remaining variable. Students are expected to make quantitative predictions using this
362
equation, and they must also be able to understand it qualitatively (HS-PS2-4).
363
364
Mathematical models, such as expressed in Newton’s Law of Gravitation,
365
provide the opportunity for students to conceptualize complex physical principles using
366
elegant equations. To assess understanding of such models, teachers can ask students
367
such questions as, “What happens to the force of gravity if one doubles the mass?”, or
368
“What happens to the force of gravity if the distance between the centers of mass of the
369
two objects is doubled?” All mathematical models in science are based on physical
370
principles of relationships between scale, proportion, and quantity. While students
371
may be mathematically adept at calculating quantities, instructors can probe for
372
understanding of the physical principles by asking questions about the equations such
373
as “Why does this equation have an “r2” value in the denominator?” or “Why does this
374
equation resemble equations for radiation intensity, sound intensity, illumination,
375
magnetism, and electrostatic forces?” This last question allows us to transition into the
376
discussion of electromagnetism.
377
Equations of Electrostatic Force
378
Working together, electricity and magnetism are a constant presence in daily life:
379
electric motors, generators, loudspeakers, microwave ovens, computers, telephone
380
systems, static cling, the warm glow of the Sun, maglev trains, and electric cars, to
381
name a few.
382
Asking students to identify the core ideas of science that are used by engineers
383
to design and improve such technologies provides opportunities to review prior learning,
384
and recognize the value of science in everyday life. It also opens the door to
385
understanding the interdependence of science, engineering, and technology, in which
386
scientists aid engineers through discoveries that can be incorporated into new devices,
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 24 of 106
First 60-Day Public Review Draft
November 2015
387
while engineers develop new instruments for observing and measuring phenomena that
388
help further scientific research.
389
While students may readily see the application of electromagnetism to machines,
390
they may have difficulty realizing that electromagnetic forces are also essential for life
391
and govern every biochemical process in their bodies. Positively charged protons hold
392
negatively charged electrons in orbit around the nucleus, and electrons of one atom are
393
attracted to protons of neighboring atoms to form a residual electromagnetic force that
394
holds molecules together, governs biochemical reactions, and ultimately prevents you
395
from falling through the floor. All chemical reactions are driven by electromagnetic
396
forces, and all chemical bonds are held together by electrochemical forces. These tiny
397
electrical interactions can add up to some very large effects. For example, our sense of
398
touch is mislabeled because we never actually “touch” anything. Instead, the electrons
399
in our hand repel the electrons from other objects and we feel this electrostatic force as
400
a sensation that objects are solid. In fact all interactions between objects in contact with
401
one another are, at their essence, electrostatic interactions.
402
Well known physicist Michio Kaku said, “You may think that I am sitting on this
403
chair, but actually that’s not true. I’m actually hovering 10 -8 cm over this chair because
404
the electrons of my body are repelling the electrons of this chair (PonderAbout 2008).”
405
How does he know? He calculates this value using Coulomb’s Law, the equation that
406
describes the force of electrically charged objects as directly proportional to the
407
magnitudes of the charges and inversely related to the square of the distances between
408
them: F=k(q1q2)/r2 , where F is the electrostatic force, k is the Coulomb’s constant, q1
409
and q2 are the magnitudes of the charges, and r is the distance between the charges.
410
Given k and any three of the variables, students should be able to calculate the value of
411
the remaining variable. (Calculating the delicate balance between gravity and
412
electrostatic forces for an entire human body and an entire chair’s worth of electrons is
413
unfortunately too complex a challenge for most students, but students can calculate the
414
force between two electrons at 10-8 cm distance apart.).
415
416
Students should notice that Coulomb’s Law is strikingly similar to Newton’s
Universal Law of Gravitation. Both forces apparently have an infinite range and are
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 25 of 106
First 60-Day Public Review Draft
November 2015
417
directly proportional to the magnitude of the component parts (the two masses or the
418
two charges), and inversely proportional to the square of the distance between them.
419
With guidance, students apply computational and mathematical thinking to conclude
420
that gravitational and electrostatic forces share a common geometry, radiating out as
421
spherical shapes from their point of origin (See snapshot below).
422
Snapshot: Coulomb’s Law, Newton’s Gravitation, and CA CCSSM Geometry
423
Imagine throwing a rock into a glassy-smooth pond. Waves emanate in all
424
directions from the point where the rock hits the surface of the pond. As a wave moves
425
from the point of impact, the same energy is spread over an increasingly large area.
426
Initially the waves are tall, but as the waves get farther from the source, they become
427
more diffuse. What is true of the water wave along the surface of the pond is similar to
428
what happens to any point source that spreads its influence equally in all directions.
429
Although the water waves are confined to the surface of the water, point sources, such
430
as radiation, sound, seismic waves, illumination, magnetism, electrostatics and gravity
431
display a similar attenuation with distance (Figure 3).
432
433
Students can model this effect mathematically with just a simple understanding of
434
the surface area of a sphere (CA CCSSM G-GMD.1). The energy from a point source
435
radiates out as a sphere so that energy initially concentrated at the source is distributed
436
over an imaginary spherical surface. To determine the intensity of the energy at a given
437
radius (r), we need to divide the source energy (S) by the surface area of the sphere to
438
which the energy is distributed. Since the surface area of a sphere can be calculated as
I1r =
S
4 pr 2 , where S is the
439
A=4r2, the intensity at one radius (r) can be calculated as
440
initial energy of the source, and I is the intensity at any radius (r) to which the energy
441
has been dispersed. As the energy continues to radiate, the intensity will decrease as a
442
function of the inverse square (1/r2) of the radius, even though the amount of energy (S)
443
remains constant. If the intensity of the energy at r=1 is defined as I1r , then the intensity
444
at r=2 will be
I2r =
1
1
I1r
I3r = I1r
4 , and the intensity at r=3 will be
9 . The intensity falls off as
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 26 of 106
First 60-Day Public Review Draft
November 2015
445
the inverse square of the distance from the source simply because the surface area of
446
the spherical front increases as a function of the radius squared.
447
448
Understanding of the geometric foundations of the inverse square principle is an
449
important tool for understanding the mathematical representations of Newton’s Law of
450
Gravitation and Coulomb’s Law (HS-PS2-4).
451
452
Figure 4. Equations representing how different phenomena all obey the inverse square
453
law. (Herr 2008, 285)
454
455
456
457
Applications of Gravitational Force: Planetary motions
In order to verify that his mathematical model of gravitation was correct, Newton
compared his results to observations of planetary orbits. If gravity was holding the
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 27 of 106
First 60-Day Public Review Draft
November 2015
458
planets in their orbits, Newton should be able to show it. He rearranged his equation in
459
order to compare its prediction to the previous work of Johannes Kepler who used
460
geometry to describe planetary motion. Indeed, Newton’s equation simplified to match
461
Kepler’s. The focus of this section is not on deriving Kepler’s Laws for elliptical orbits
462
directly from the gravitational force, but instead on interpreting the evidence of the
463
orbital period of different bodies in our solar system, including planets and comets.
464
These laws form an excellent illustration of the crosscutting concept of scale,
465
proportion, and quantity. By comparing the distance of objects away from the Sun
466
and the time it takes them to complete one orbit, students recognize a pattern.
467
Table 2 shows that the ratio determined by Kepler (orbital period squared divided by
468
orbital distance cubed) is nearly constant for objects in our solar system. Students can
469
calculate this ratio for Earth and other planets and then make measurements of the
470
orbital path of comets to try estimate how often they will return. The ratio is only true for
471
objects orbiting the same body (illustrated by the dramatically different ratio for the
472
Moon in
473
Table 2), but students can use measurements of the Moon to predict the height of
474
satellites in geosynchronous orbit (they have an orbital period of exactly one day, which
475
allows them to always be in the same position in the sky. Satellite Television receives
476
signals from these satellites), or the orbital period of the International Space Station
477
from its height above Earth. Students can also the more complete form of Kepler’s laws
478
to calculate the mass of distant stars using only the orbital period of newly discovered
479
planets that orbit them.
480
481
Table 2. Objects far away from the Sun take longer to orbit it, but ratios using Kepler’s
482
Laws are nearly the same for all bodies in our solar system.
Period
Average Distance
Kepler’s ratio: T2/R3
Planet
(yr)
(AU)
(yr2/AU3)
Mercury
0.241
0.39
0.98
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 28 of 106
First 60-Day Public Review Draft
November 2015
Venus
0.615
0.72
1.01
Earth
1
1
1.00
Mars
1.88
1.52
1.01
Jupiter
11.8
5.2
0.99
Saturn
29.5
9.54
1.00
Uranus
84
19.18
1.00
Neptune
165
30.06
1.00
Pluto
248
39.44
1.00
Halley’s comet
75.3
17.8
1.00
Comet Hale Bopp
2,521
186
0.99
0.0766
0.00257
345667*
Moon (relative to
Earth)*
483
* Kepler’s ratio only works for objects orbiting around the same body. Since Moon orbits
484
Earth, its ratio should be much different.
485
486
Engineering Connection: Computational models of orbits
487
When a company spends millions of dollars to launch a
488
communications satellite or the government launches a new weather
489
satellite, they employ computer models of orbital motion to make sure
490
these investments will stay in orbit. These models are based on the exact equations
491
introduced in the CA NGSS high school courses. In fact, students can gain a deeper
492
understanding of the orbital relationships and develop computational thinking skills by
493
interacting directly with computer models of simple two body systems. Even with
494
minimal computer programming background, students could learn to interpret an
495
existing computer program of a two-body gravitational system. They could start by being
496
challenged to identify an error in the implementation of the gravity equations in sample
497
code given to them. Next, students modify the code to correctly reflect the mass of the
498
Earth and a small artificial communications satellite orbiting around it. They can vary
499
different parameters in the code such as the distance from Earth or initial speed and
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 29 of 106
First 60-Day Public Review Draft
November 2015
500
see how those parameters affect the path of the satellite. At what initial launch speeds
501
will the satellite stay in orbit versus spiral back into Earth’s atmosphere?
502
503
While Kepler’s laws present a simple view of orbital shapes and periods, the
504
NRC Framework pushes teachers to emphasize the importance of changes in orbits,
505
as these changes have large impacts on Earth’s internal systems:
506
Orbits may change due to the gravitational effects from, or collisions with, other
507
objects in the solar system. Cyclical changes in the shape of Earth’s orbit around
508
the sun, together with changes in the orientation of the planet’s axis of rotation,
509
both occurring over tens to hundreds of thousands of years, have altered the
510
intensity and distribution of sunlight falling on Earth. These phenomena cause
511
cycles of ice ages and other gradual climate changes. (National Research
512
Council 2012, 176)
513
514
Using realistic computer simulations of Earth’s orbit, students can investigate the
515
effects collisions (such as the impact that led to the creation of the Moon) or explore the
516
variation in the Earth-Sun distance to look for evidence of cyclic patterns. They would
517
discover some cyclic patterns called Milankovitch cycles, which have strong influence
518
on Earth’s ice age cycles.
519
Applications of Electrical and Magnetic Forces
520
The instructional segment then moves on to examining electromagnetic effects in
521
solid matter. In this part of the instructional segment, connections should also be made
522
to the electromagnetic interactions within and between molecules and the idea of
523
chemical bonds. At the middle grade level, students were asked to develop conceptual
524
models of the structure of solids, liquids and gases (MS-PS1-4). Here they work to
525
develop and refine those models, and to understand that the stability and properties of
526
solids depend on the electromagnetic forces between atoms, and thus on the types and
527
patterns of atoms within the material. Key to this step is an understanding of the
528
substructure of an atom, and of how the mass of the atom is determined by its nucleus,
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 30 of 106
First 60-Day Public Review Draft
November 2015
529
but its electronic structure extends far outside the region where the nucleus sits. An
530
important idea here is that the geometric size of more massive atoms is not very
531
different from that of a hydrogen atom, and an explanation for this is the fact that the
532
higher charge of the nucleus pulls the electrons more strongly, so though there are
533
more electrons, and their patterns are more complex, there is a roughly common size
534
scale for all atoms. Models for materials help make the importance of this fact visible,
535
as students see that you can fit many different combinations of atoms together in space,
536
and thus make a great variety of molecules and materials. Once again, at this level the
537
understanding expected is qualitative, not quantitative, but students should experience
538
and consider a wide range of different types of materials, including some biological
539
examples, to build an idea of the power of understanding forces in materials and the
540
variety of consequences that can arise from their electromagnetic substructure.
541
Most collegiate STEM education is highly departmentalized, with students
542
majoring in biology, chemistry, geology, astronomy, physics, engineering, mathematics
543
or related fields. Students may inadvertently assume that particular topics belong to one
544
domain or another and may fail to see the elegance and power of crosscutting concepts
545
that have applications in a variety of fields. Teachers and students of physics may
546
therefore have difficulty understanding the relevance of such performance expectations
547
as HS-PS2-6, which states that students shall “communicate scientific and technical
548
information about why the molecular-level structure is important in the functioning of
549
designed materials.” This performance expectation sounds like it belongs in a
550
chemistry course because it deals with “molecular-level structure”, or perhaps in
551
engineering since it deals with the “functioning of designed materials”. In reality, this
552
performance expectation, like many, can be equally valuable in the study of chemistry,
553
engineering and/or physics. After studying electromagnetic interactions, students are
554
better prepared to study the attractive and repulsive forces that determine the properties
555
of matter.
556
HS-PS2-6 requires students to obtain, evaluate, and communicate
557
information related to the properties of various materials and their consequent
558
usefulness in particular applications. As stated in Appendix-M (Connections to the
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 31 of 106
First 60-Day Public Review Draft
November 2015
559
Common Core State Standards for Literacy in Science and Technical Subjects) of the
560
NGSS, “reading in science requires an appreciation of the norms and conventions of the
561
discipline of science, including understanding the nature of evidence used, an attention
562
to precision and detail, and the capacity to make and assess intricate arguments,
563
synthesize complex information, and follow detailed procedures and accounts of events
564
and concepts.” Students “need to be able to gain knowledge from elaborate diagrams
565
and data that convey information and illustrate scientific concepts. Likewise, writing
566
and presenting information orally are key means for students to assert and defend
567
claims in science, demonstrate what they know about a concept, and convey what they
568
have experienced, imagined, thought, and learned.” HS-PS2-6 emphasizes these skills.
569
Students may study the molecular-level interactions of various conductors,
570
semiconductors and insulators to explain why their unique properties make them
571
indispensable in the design of integrated circuits or urban power grids. For example, if
572
students understand that the fundamental structure of metals, such as copper,
573
aluminum, silver, and gold, can be described as a myriad of nuclei immersed in a “sea
574
of mobile electrons”, they can then explain that these materials make good conductors
575
because the electrons are free to migrate between nuclei under applied electromagnetic
576
forces. By contrast, when students investigate the molecular level properties of covalent
577
compounds, such as plastics and ceramics, they should note that they behave as
578
electrical insulators because their electrons are locked in bonds and therefore resistant
579
to the movement that is necessary for electric currents. As students learn to
580
communicate such information, they obtain a better appreciation of cause and effect.
581
For example, students should be able to explain that electromagnetic interactions at the
582
molecular level (causes) result in properties (effects) at the macro-level, and that these
583
properties make certain materials good candidates for specific technical applications.
584
The role of engineering in this instructional segment is not to make a design, but
585
to use engineering thinking to analyze and explain a designed or natural material, and
586
to communicate conclusions about how the substructure relates to the macroscopic
587
properties of the material.
588
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 32 of 106
First 60-Day Public Review Draft
November 2015
589
Physics - Instructional segment 3: Energy Conversion and Renewable
Energy
Guiding Questions:

How do power plants generate electricity?

What engineering designs can help increase the efficiency of our
electricity production and reduce the negative impacts of using fossil
fuels?
Science and Engineering Practices:

Developing and using models
Crosscutting concepts:

Energy and matter: Flows, cycles, and conservation
Students who demonstrate understanding can:
HS-PS2-5 Plan and conduct an investigation to provide evidence that an
electric current can produce a magnetic field and that a changing
magnetic field can produce an electric current. [Assessment
Boundary: Assessment is limited to designing and conducting
investigations with provided materials and tools.]
HS-PS3-1. Create a computational model to calculate the change in the
energy of one component in a system when the change in energy
of the other component(s) and energy flows in and out of the
system are known. [Clarification Statement: Emphasis is on explaining
the meaning of mathematical expressions used in the model.]
[Assessment Boundary: Assessment is limited to basic algebraic
expressions or computations; to systems of two or three components;
and to thermal energy, kinetic energy, and/or the energies in
gravitational, magnetic, or electric fields.]
HS-PS3-2 Develop and use models to illustrate that energy at the
macroscopic scale can be accounted for as a combination of
energy associated with the motions of particles (objects) and
energy associated with the relative position of particles (objects).
[Clarification Statement: Examples of phenomena at the macroscopic
scale could include the conversion of kinetic energy to thermal energy,
the energy stored due to position of an object above the earth, and the
energy stored between two electrically-charged plates. Examples of
models could include diagrams, drawings, descriptions, and computer
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 33 of 106
First 60-Day Public Review Draft
November 2015
simulations.]
HS-PS3-5 Develop and use a model of two objects interacting through
electric or magnetic fields to illustrate the forces between objects
and the changes in energy of the objects due to the interaction.
[Clarification Statement: Examples of models could include drawings,
diagrams, and texts, such as drawings of what happens when two
charges of opposite polarity are near each other.] [Assessment
Boundary: Assessment is limited to systems containing two objects.]
HS-PS3-3. Design, build, and refine a device that works within given
constraints to convert one form of energy into another form of
energy.* [Clarification Statement: Emphasis is on both qualitative and
quantitative evaluations of devices. Examples of devices could include
Rube Goldberg devices, wind turbines, solar cells, solar ovens, and
generators. Examples of constraints could include use of renewable
energy forms and efficiency.] [Assessment Boundary: Assessment for
quantitative evaluations is limited to total output for a given input.
Assessment is limited to devices constructed with materials provided to
students.]
HS-PS4-5. Communicate technical information about how some
technological devices use the principles of wave behavior and
wave interactions with matter to transmit and capture information
and energy.* [Clarification Statement: Examples could include solar
cells capturing light and converting it to electricity; medical imaging; and
communications technology.] [Assessment Boundary: Assessments are
limited to qualitative information. Assessments do not include band
theory.]
HS-ESS3-2. Evaluate competing design solutions for developing,
managing, and utilizing energy and mineral resources based on
cost-benefit ratios.* [Clarification Statement: Emphasis is on the
conservation, recycling, and reuse of resources (such as minerals and
metals) where possible, and on minimizing impacts where it is not.
Examples include developing best practices for agricultural soil use,
mining (for coal, tar sands, and oil shales), and pumping (for petroleum
and natural gas). Science knowledge indicates what can happen in
natural systems—not what should happen.]
HS-ETS1-1. Analyze a major global challenge to specify qualitative and
quantitative criteria and constraints for solutions that account for
societal needs and wants.
HS-ETS1-2. Design a solution to a complex real-world problem by breaking
it down into smaller, more manageable problems that can be
solved through engineering.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 34 of 106
First 60-Day Public Review Draft
November 2015
HS-ETS1-3. Evaluate a solution to a complex real-world problem based on
prioritized criteria and trade-offs that account for a range of
constraints, including cost, safety, reliability, and aesthetics as
well as possible social, cultural, and environmental impacts.
HS-ETS1-4. Use a computer simulation to model the impact of proposed
solutions to a complex real-world problem with numerous criteria
and constraints on interactions within and between systems
relevant to the problem.
Significant Connections to California’s Environmental Principles and Concepts
Principle III Natural systems proceed through cycles that humans depend upon,
benefit from and can alter.
Principle IV The exchange of matter between natural systems and human
societies affects the long term functioning of both.
Principle V Decisions affecting resources and natural systems are based on a
wide range of considerations and decision-making processes.
590
591
Background for Teachers and Instructional Suggestions
We use energy every moment of every day, but where does it all come from?
592
Our body utilizes energy stored in the chemical potential energy of bonds between the
593
atoms of our food, which were rearranged within plants using energy from the Sun. The
594
light energy shining out from our computer was converted from the electric potential
595
energy of electrons from the wall socket that flowed through wires that may trace back
596
to a wind turbine, which did work harnessing the movement of air masses, which
597
absorbed thermal energy from the solid Earth, which originally absorbed the energy
598
from the Sun. Each of these examples represents the flow of energy within different
599
components of the Earth system. With each interaction, energy can change from one
600
form to another. These ideas comprise perhaps the most unifying crosscutting concept
601
in physics and all other science, conservation of energy. The first law of
602
thermodynamics elaborates on this idea by saying that the total energy of an isolated
603
system is constant, and that although energy can be transformed from one form to
604
another, it cannot be created nor destroyed. Conservation of energy requires that
605
changes in energy within a system must be balanced by energy flows into or out of the
606
system by radiation, mass movement, external forces, or heat flow. The vignette for the
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 35 of 106
First 60-Day Public Review Draft
November 2015
607
4-course physics provides a framework for discussing many of these energy forms and
608
how they convert from one to another. This instructional segment selects a subset of
609
processes that follow a storyline of tracing the energy flow of our electricity back to
610
various power plants and renewable energy sources. This approach provides
611
integration with timely issues in engineering and Earth science.
612
Electricity in Daily Life
613
Before students jump into the physical processes that allow us to generate
614
electricity, students should be able to compare the range of different electricity
615
generation methods currently utilized. This basic familiarity will make all of the physical
616
principles more tangible, but it also allows students to engage in a real-world decision
617
making process (EP&C Principle V) because each of these energy sources has
618
advantages and disadvantages (ESS3.A). More than half of the electricity in California
619
was generated from fossil fuels in 2013 (California Energy Commission Energy
620
Almanac 2015). Many fossil fuel power plants emit toxic pollutants and can impact the
621
health of ecosystems and people nearby (EP&C Principles IV). Fossil fuels also emit
622
greenhouse gases that do not have a direct impact on health but contribute to global
623
climate change (ESS2.D; EP&C Principle III; HS Chemistry course instructional
624
segment 4). At the same time, these fuel sources are cheap and plentiful. New
625
technology in the last few years has made other energy sources increasingly viable and
626
California has pledged to increase the use of these renewable energy sources to one
627
third of California’s electricity supply by 2020 (up from less than 20% a decade earlier).
628
What issues have been driving California’s decisions? Excellent classroom resources
629
exist for teaching about different electricity generation strategies, including formats
630
where students debate the relative costs and benefits of each energy source 1 (HS-
631
ESS3-2).
1
http://www.switchenergyproject.com/education/CurriculaPDFs/SwitchCurricula-
Secondary-Introduction/SwitchCurricula-Secondary-GreatEnergyDebate.pdf
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 36 of 106
First 60-Day Public Review Draft
632
633
November 2015
The Physics of Power Plants
A power plant can be thought of a system, and energy is constantly flowing out
634
of the system in the form of electricity. The energy in all systems is finite, so a power
635
plant would quickly run out of energy if it didn’t have a constant source of fuel. Each
636
power plant is built to produce a certain amount of energy in a given time (i.e., “power”),
637
and the power output of most plants can be easily found. Students can use internet
638
resources to find the power generation capacity and fuel source of the power plant
639
closest to their school. They can then create a mathematical model (HS-PS3-1) to
640
calculate the amount of fuel required to operate the power plant in a day or a year,
641
knowing that the electrical energy flowing out of the system has to equal the energy
642
from the fuel sources entering into the system (at this point, students can neglect
643
efficiency – it will be introduced later).
644
At the middle grade level, students have explored various forms of energy,
645
determining the factors that affect kinetic energy (MS-PS3-1) and potential energies
646
(MS-PS3-2), the relationship between kinetic energy and thermal energy (MS-PS3-4),
647
and the concept of energy transfer in engineering design (MS-PS3-3) and scientific
648
explanations (MS-PS3-5). Clarification statements for several of these PEs explicitly
649
state that calculations are excluded from the middle grade level. In high school,
650
students are now ready to quantify the amount of energy objects have and transfer
651
during interactions. The high school chemistry course also pays explicit attention to
652
these topics with emphasis on thermal and chemical potential energies.
653
The middle grade PEs are written broadly such that students might come into
654
high school with knowledge of different forms of energy. Here, students should
655
organize what they know about these different forms of energy to make the distinction
656
between energy from particle motion, potential energy due to interactions between
657
particles, and radiation. Potential energies arise from forces that act at a distance like
658
gravity and electromagnetism (as discussed in instructional segment 2). Students
659
“develop and use a model that energy at the macroscopic scale can be accounted for
660
as a combination of energy associated with the motions of particles (objects) and
661
energy associated with the relative position of particles (objects)” (HS-PS3-2). In other
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 37 of 106
First 60-Day Public Review Draft
November 2015
662
words, the sum of the kinetic and potential energy of component particles (energy of
663
motion and position) must total the bulk energy measured at the macroscopic level.
664
Using diagrams, drawings, descriptions, and/or computer simulations, students should
665
be able to illustrate this summative relationship. This performance expectation is
666
designed to help students bridge concepts traditionally associated with chemistry (e.g.
667
the energy of atoms and molecules) with the concepts traditionally associated with
668
physics (e.g. the energy of macroscopic objects). Students can develop this model by
669
making a poster of the different stages in a typical thermoelectric power plant (Figure 5).
670
To generate electricity, these power plants use heat energy to eventually produce
671
electricity (most fossil fuel, nuclear, geothermal, and even concentrated solar power
672
plants fit in this category). They usually heat water into steam, which changes the
673
relative position of the particles from being densely packed in a liquid into particles that
674
are much farther apart. This change in relative position requires an increase in the
675
electrostatic potential energy of the water molecules, which we see macroscopically as
676
having ‘absorbed’ the latent heat of vaporization. The power plants then convert thermal
677
energy into kinetic energy during one stage of their process. Individual molecules
678
(usually water molecules heated to steam) are moving very fast and collide with a
679
turbine, transferring some of the kinetic energy in randomly moving molecules (i.e.,
680
thermal energy) into the systematic motion of the turbine (i.e., kinetic energy of the
681
object). The turbine will turn the crank of a generator to convert the kinetic energy into
682
electricity, but it will not be 100% efficient because molecular collisions will result in
683
energy being transferred to particles moving in random directions again, detracting from
684
the total energy available in the object to move the crank forward. At the macroscopic
685
level, we attribute this lower efficiency to the process we call friction. At each stage,
686
students communicate the forms of energy at both the microscopic and macroscopic
687
level.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 38 of 106
First 60-Day Public Review Draft
November 2015
688
689
Figure 5. Schematic of a power plant. (Center for Climate and Energy Solutions 2015)
690
Converting Kinetic Energy to Electricity
691
Electric generators are an essential component in nearly all types of electric
692
power generation, including coal, nuclear, natural gas, geothermal, tidal, wind turbines,
693
hydroelectric (basically everything except fuel cells and solar photovoltaic). Students
694
might try to apply their understanding of microscopic collisions to the energy conversion
695
processes within a generator to come to the incorrect conclusion that these collisions
696
impart kinetic energy to electrons, which move through a circuit. In order to overcome
697
this misconception, students must replace that notion with a correct model for energy
698
conversion between kinetic energy of objects and electricity. This model requires that
699
students continue their exploration of electric and magnetic forces from instructional
700
segment 2.
701
For many years, scientists considered the electricity and magnetism to be
702
independent of each other. In 1819 Hans Christian Øersted discovered that electric
703
current generates a magnetic force, and in 1839, Michael Faraday showed that
704
magnetism could be used to generate electricity. Each discovery demonstrated that the
705
two were connected, but it was not until 1860 that James Clerk Maxwell developed a
706
mathematical model to show how electricity and magnetism are related. During this
707
section, students will follow in the footsteps of these famous scientists by planning and
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 39 of 106
First 60-Day Public Review Draft
November 2015
708
carrying out investigations that illustrate the interactions between electricity and
709
magnetism (HS-PS2-5). These interactions are essential for understanding how most
710
electricity is generated in power plants.
711
Students need to experience multiple situations to develop a model that
712
changing the magnetic field through a conductive (wire) loop can cause an electric
713
current to flow in the loop, and that a current flowing in a wire creates a magnetic field
714
around the wire. Much like changing and dynamic mechanical forces in unit 1’s egg
715
drop can be analyzed one snapshot in time after another, these processes that involve
716
changing fields build upon the understanding of static electric forces defined by
717
Coulomb’s Law in instructional segment 2. Drawing explicit connections between the
718
static and time-varying cases is essential to understanding the relationship. Classroom
719
activities should highlight application of these principles to electrical generators
720
(turbines), electrical motors, and the myriad of applications of these principles in devices
721
in our homes.
722
723
Figure 6 Students can plan and conduct a variety of investigations to provide evidence
724
that an electric current can produce a magnetic field and that a changing magnetic field
725
can produce an electric current. (Privat-Deschanel 1876)
726
Teachers might show Øersted’s simple experiment in which he noticed that a
727
compass needle would be deflected from magnetic north when an electric current
728
passed through a wire that was held above the magnet (Figure 6a). Students should be
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 40 of 106
First 60-Day Public Review Draft
November 2015
729
encouraged to examine a variety of variables to characterize this relationship. For
730
example, they can vary the direction of the wire, the voltage through the wire, and the
731
number of winds of the wire around the compass (Figure 6b). Eventually they should
732
discover that the deflection is greatest when the wire is aligned with the north/south
733
orientation of the compass needle. In addition, they will notice that this effect is
734
magnified by increasing the applied voltage or by increasing the number of winds
735
around the compass and that a circular field exists around a current-carrying wire
736
(Figure 6c). It should be emphasized that students are not just trying to verify Øersted’s
737
findings, but rather test variables to see their effect on creating a magnetic field to which
738
the compass needle responds. Students can also place iron filings on a glass plate that
739
lies on top of their wire coil and use that to map out the strength and orientation of the
740
magnetic field. As they tap on the plate, the filings align with the magnetic field, with
741
greater concentrations moving to those locations where the field is strongest. Adding a
742
second magnet, students can use the iron filings to visualize the interaction between
743
objects. Equipped with data on the direction and relative magnitude of the field, students
744
can draw a qualitative model of the magnetic field using vectors at various locations
745
surrounding the bar magnet (HS-PS3-5). In such a model, the direction of the field is
746
indicated by the direction of arrows, while its magnitude is indicated by the length of
747
these arrows. Upon analyzing and interpreting their data, students should be asked if
748
they can see any engineering applications to this phenomenon, and discover that it is
749
the basis for electric motors.
750
After seeing that an electric current creates a magnetic field, students should see
751
if the reverse is also true. Once again, they should plan and carry out an
752
investigation to see if a changing magnetic field can induce an electric current. The
753
simplest investigation requires connecting a galvanometer to a wire loop to measure
754
electric current in the wire. As they move the wire back and forth between two strong
755
magnets (Figure 6d), students will observe the galvanometer needle deflect in opposite
756
directions depending on which way the wire is moved (indicating that the electric current
757
flows in different directions). Students should be encouraged to use this equipment to
758
explore other variables. For example, they may coil the wire and move the magnet
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 41 of 106
First 60-Day Public Review Draft
November 2015
759
through the center of the coil and see a similar response but generating a stronger
760
electric current (Figure 6e). Upon analyzing and interpreting their data, students
761
should be asked if they can see any engineering applications to this phenomenon, and
762
discover the basis for electric generators.
763
Converting Light to Electricity
764
Solar panels convert light energy into electricity. Students will learn more about
765
the nature of light in instructional segment 5, but the focus in this instructional segment
766
is on understanding the qualitative interactions between light energy and the matter in
767
solar cells well enough to communicate it to others (HS-PS4-5). Atoms in a solar cell
768
absorb the light energy, which causes electrons to be knocked loose. Free electrons are
769
a key ingredient to an electric current, but currents require those electrons to move
770
systematically around a circuit. Silicon semiconductors are set up so that they have a
771
systematic bias where electrons preferentially move in a single direction. How does this
772
happen? Pure silicon forms systematic crystal structures, but adding small amounts of
773
some types of elements disrupts those shapes and can even allow each silicon atoms
774
to be in a configuration where it can accept an additional electron. Adding other specific
775
elements causes the silicon atoms in the lattice to end up with an extra electron.
776
Engineers make thin crystals of each type (one with contaminants that have extra
777
electrons and one with ‘holes’ for additional electrons) and stack them on top of one
778
another. Now, when light hits the atoms in this material, the free electrons are repelled
779
by the extra electrons in one layer and automatically move towards the layer with space
780
for additional electrons. As the Sun continues to shine and more electrons get knocked
781
loose, they always flow in the same direction and set up a steady electric current.
782
Students must be able to understand this interaction between light and matter well
783
enough to communicate it to others (HS-PS4-5). Groups of students could make a fact
784
sheet, a stop-motion animation, or skit to articulate the ideas.
785
Snapshot: Evaluating plans for renewable power plants
The city where Mrs. G’s city is located wants to build a new renewable energy power
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 42 of 106
First 60-Day Public Review Draft
November 2015
plant. They are considering two options, a series of small hydroelectric power dams
on a river coming out of the mountains and a set of windmills in the flat sections of
town where it is always windy. Mrs. G divides the class into small groups and she
assigns each one to either create a proposal for wind energy or a plan for
hydroelectric power. Teams begin by using mathematical thinking to calculate the
amount of energy their proposed project would generate. The hydroelectric group
assumes that the dams will harness gravitational potential energy and use the
appropriate equations to evaluate the energy produced by different height dams
(Energy = mass x g x height, where the water mass is determined by the average
annual flow rate on the rive calculated using data collected by a USGS stream gauge
that is available on the internet). The wind energy group assumes that the kinetic
energy of the air is harnessed and uses the appropriate equations to evaluate the
energy produced by different sized windmills (Energy = ½ x mass x velocity2, where
the mass is calculated using the average density of air combined with the size of the
blades and the speed of the wind. Wind velocity is calculated using the average
values from a nearby weather station that posts hourly data on the internet). Mrs. G
teaches the students about the concept of efficiency when it comes to electric power
generation where only a fixed proportion of the energy is actually successfully
converted to electricity (while a large fraction is wasted as heat). Each team obtains
information about the efficiency of their energy generation technology and uses it
update their estimate of the electrical energy they can generate. With these basic
calculations, each team must develop a specific proposal for a power plant that will
provide 30% of the city’s energy. The wind teams must decide how many windmills,
and the diameter of the blades. The hydroelectric teams must decide how many dams
and their heights. Each team produces a report outlining the benefits of their plan. The
class then hosts a town hall meeting where teams communicate their plans and
present an argument that their proposal is better than the competing plans. This
argument should be supported by evidence that goes beyond the simple energy
calculations but also takes into account the relative benefits and impacts of each
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 43 of 106
First 60-Day Public Review Draft
November 2015
technology on natural systems (EP&C II; for example, dams destroy aquatic habitat,
use large volumes of CO2 in their cement, and result in water lost to evaporation; wind
turbines obstruct scenic views, occupy large amounts of land, and only provide
intermittent energy). These competing factors enter into all real world decisions about
energy generation (EP&C V).
Science and engineering
practices
Disciplinary core ideas

PS3.A Definitions of

Energy
PS3.B Conservation of
Energy and Energy

Transfer
PS3.D Energy and
Chemical Processes in
Everyday Life
ESS3.A Natural Resources
ESS3.C Human Impacts on
Earth Systems
ESS3.D Global Climate
Change


Using mathematics and
computational thinking
Engaging in argument
from evidence
Obtaining, evaluating
and communicating
information
Crosscutting concepts
Energy and matter:
Flows, cycles, and
conservation
Influence of science,
engineering, and
technology on society
and the natural world
Connections to the CA CCSSM:
Connections to CA CCSS for ELA/Literacy:
Connection to CA ELD Standards :
Connections to the CA EP&Cs: II, V
786
787
Engineering Energy Conversion Devices
Now that students have learned extensively about the theory behind energy
788
conversion devices, they are now tasked with an engineering challenge to create one
789
themselves (HS-PS3-3). The vignette in High School Four Course Model – Physics
790
section of this Science Framework includes a template of what this design challenge
791
might look like. The first stage of the engineering design process is to place the goal in
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 44 of 106
First 60-Day Public Review Draft
November 2015
792
the context of the major global challenge of providing affordable electrical energy
793
without the problems associated with fossil fuels (HS-ETS1-1). Students evaluated the
794
impacts of different electricity sources at beginning of this instructional segment,
795
including a discussion of how fossil fuels contribute to global climate change. The High
796
School Three Course Model – Chemistry in the Earth System course emphasizes
797
physical mechanisms causing climate change and the High School Three Course Model
798
– The Living Earth
799
course explores its effects on the biosphere. Depending on the sequence of courses
800
within each school district, this instructional segment should draw strong connections to
801
those courses. Designing, building, and improving energy conversion devices that are
802
more efficient or that pollute less involves breaking down the complex global problem
803
into more manageable problems that can be solved through engineering (HS-ETS1-2).
804
Students have learned some of the scientific principles behind the engineering tools that
805
can help address the challenge throughout this instructional segment. Students now
806
choose to build their own wind turbines, hydroelectric power plants, solar panels, or
807
other mini version of a power plant that transforms energy from less useful forms, such
808
as wind, sunlight, or motion, into electricity (arguably the most convenient and useful
809
form of energy in our modern world). Students learn to work within engineering
810
constraints as they strive to maximize efficiency (generate the largest power output
811
possible) while taking into account prioritized criteria and trade-offs (HS-ETS1-3).
812
Students can measure outputs and then refine their designs to maximize efficiency
813
given constant inputs. Students can also utilize existing computer simulations to
814
investigate the impact of these different energy solutions (HS-ETS1-4).
815
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 45 of 106
First 60-Day Public Review Draft
November 2015
816
817
Physics - Instructional segment 4: Nuclear Processes and Earth History
Guiding Questions:
 What does E=mc2 mean?
 How do nuclear reactions illustrate conservation of energy and mass?
 How do we determine the age of rocks and other geologic features?
Science and Engineering Practices:
 Developing and using models
Crosscutting concepts:
 Energy and matter: Flows, cycles, and conservation
Students who demonstrate understanding can:
HS-PS1-8 Develop models to illustrate the changes in the composition of
the nucleus of the atom and the energy released during the
processes of fission, fusion, and radioactive decay. [Clarification
Statement: Emphasis is on simple qualitative models, such as pictures
or diagrams, and on the scale of energy released in nuclear processes
relative to other kinds of transformations.] [Assessment Boundary:
Assessment does not include quantitative calculation of energy
released. Assessment is limited to alpha, beta, and gamma radioactive
decays.]
HS-ESS1-5. Evaluate evidence of the past and current movements of
continental and oceanic crust and the theory of plate tectonics to
explain the ages of crustal rocks. [Clarification Statement: Emphasis
is on the ability of plate tectonics to explain the ages of crustal rocks.
Examples include evidence of the ages oceanic crust increasing with
distance from mid-ocean ridges (a result of plate spreading) and the
ages of North American continental crust increasing with distance away
from a central ancient core (a result of past plate interactions).]
HS-ESS1-6. Apply scientific reasoning and evidence from ancient Earth
materials, meteorites, and other planetary surfaces to construct an
account of Earth’s formation and early history. [Clarification
Statement: Emphasis is on using available evidence within the solar
system to reconstruct the early history of Earth, which formed along with
the rest of the solar system 4.6 billion years ago. Examples of evidence
include the absolute ages of ancient materials (obtained by radiometric
dating of meteorites, moon rocks, and Earth’s oldest minerals), the sizes
and compositions of solar system objects, and the impact cratering
record of planetary surfaces.]
HS-ESS2-1. Develop a model to illustrate how Earth’s internal and surface
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 46 of 106
First 60-Day Public Review Draft
November 2015
processes operate at different spatial and temporal scales to form
continental and ocean-floor features. [Clarification Statement:
Emphasis is on how the appearance of land features (such as
mountains, valleys, and plateaus) and sea-floor features (such as
trenches, ridges, and seamounts) are a result of both constructive forces
(such as volcanism, tectonic uplift, and orogeny) and destructive
mechanisms (such as weathering, mass wasting, and coastal erosion).]
[Assessment Boundary: Assessment does not include memorization of
the details of the formation of specific geographic features of Earth’s
surface.]
818
Background for Teachers and Instructional Suggestions
Energy related to changes in the nuclei of atoms drives about 20% of California’s
819
820
electricity generation (California Energy Commission Energy Almanac 2015) (from
821
fission in nuclear power plants), half the heat flowing upwards from Earth’s interior (from
822
the radioactive decay of unstable elements) (Gando et al. 2011), all of the energy we
823
receive from the Sun (from nuclear fusion in its core). In this instructional segment,
824
students will develop models for these processes. Students will need to apply an
825
understanding of the internal structure of atoms and be able to read the periodic table,
826
topics introduced in the high school chemistry class and no longer addressed at the
827
middle grade level. If students have not yet taken high school chemistry, teachers can
828
use nuclear processes to introduce these topics.
829
Changes in the nucleus occur at a length scale too small to observe directly, but
830
students can detect evidence of these processes by looking at energy and matter that
831
radiate out of the nucleus as a result of these changes. One can think of these
832
emissions as an effect and develop a model that explains the cause. Students begin
833
the instructional segment by making observations of a cloud chamber2 (as a video clip
834
or classroom demonstration). Strange streaks whiz through the cloud chamber.
835
Students can measure background radiation using a Geiger counter or even a
2
MIT Video, Cloud Chamber: http://video.mit.edu/watch/cloud-chamber-4058/
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 47 of 106
First 60-Day Public Review Draft
November 2015
836
smartphone app3. With these observations, students now obtain information about the
837
discovery of radioactivity and how scientists in the late 1800’s like Becquerel and the
838
Curies determined that the particles they see had mass, were often charged, and
839
emanated in high concentrations from different types of natural materials. Over time,
840
this understanding has led to the modern models of radioactivity and the modern tools
841
for measuring its effects. These concepts can generally not be explored in direct
842
experimentation in the classroom, so access to and analysis of data from external
843
sources and use of simulations will play an important role in engaging students in three-
844
dimensional learning.
845
Scientists know of only four fundamental interactions, also known as fundamental
846
forces: gravitational, electromagnetic, strong nuclear and weak nuclear. All interactions
847
between matter in the Universe involve one of these forces. Students studied the first
848
two during instructional segment 2, and the focus in this instructional segment is on the
849
effects of the remaining two. The strong force ensures the stability of ordinary matter
850
by binding the atomic nucleus together, while the weak mediates radioactive decay.
851
Although the strong and weak nuclear forces are essential for matter, as we know it, to
852
exist, they are difficult to conceptualize and relate to because they operate at distances
853
scales too small to be seen. As the nucleus gets larger, forces holding nuclei together
854
are overcome by electrostatic repulsion, which is why the largest atoms on the periodic
855
table are unstable. It is this instability that result in the nucleus changing in one or more
856
ways.
857
The Earth receives more energy from the Sun in an hour and a half than all of
858
humanity uses in a year, but this energy does not come from nothing. Nuclear reactions,
859
too, must obey conservation laws, but now students must apply the principle of mass-
860
energy equivalence (E=mc2) to revise the view that matter is conserved as atoms, to a
3
Australian Nuclear Science and Technology Organization, Smart phone radiation
detector ‘app’ tests positive:
http://www.ansto.gov.au/AboutANSTO/MediaCentre/News/ACS049898
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 48 of 106
First 60-Day Public Review Draft
November 2015
861
more accurate view that the number of nucleons (sum of protons and neutrons) is
862
conserved. Neither mass, nor the number of atoms of each type are conserved in
863
nuclear processes, and although such mass conservation “laws” are applicable to
864
gravitational and electromagnetic processes they must be revised and refined as we
865
examine nuclear processes, This revision and refinement process should be stressed
866
as an essential part of the nature of science.
867
Nuclear changes all release large amounts of energy, but they do so by different
868
mechanisms. Scientists have recognized several classes of nuclear processes,
869
including combining small nuclei to make larger ones (fusion) and larger nuclei emitting
870
smaller pieces (fission, alpha decay, and beta decay). Students develop models to
871
illustrate the changes in the composition of the nucleus of the atom and the energy
872
released during each of these processes (HS-PS1-8). Such models could be in the form
873
of equations or diagrams (Figure 7). Although it is not necessary to include quantitative
874
calculations, the models should communicate the conservation of the combined mass-
875
energy system.
876
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 49 of 106
First 60-Day Public Review Draft
November 2015
877
878
Figure 7 Students should be able to develop models to illustrate the changes in the
879
composition of the nucleus of the atom and the energy released during the processes of
880
fission, fusion, and radioactive decay. (Pares Space Warp Research 2015; Thomas
881
Jefferson National Accelerator Facility – Office of Science Education 2015)
882
In fusion, small nuclei combine together to form larger ones. Since all nuclei have
883
positive charges (made only of positive protons and neutral neutrons), electrostatic
884
forces will tend to repel nuclei apart from one another. The closer nuclei get to one
885
another, the stronger the electrostatic repulsion. Nuclei can get very close to one
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 50 of 106
First 60-Day Public Review Draft
November 2015
886
another if they collide when they are moving very fast. If they manage to get close
887
enough to one another, another interaction becomes important: the strong nuclear force
888
which is what holds nuclei together in the first place. Like creating a new chemical bond,
889
creating new strong force interactions releases energy. Students will revisit fusion and
890
apply their qualitative model of it to stars in instructional segment 6, since stellar cores
891
are the only place where fusion naturally occurs. Efforts have been made to use fusion
892
to make energy on Earth, but the engineering task is challenging. If scientists and
893
engineers can get it to work, fusion would be cleaner and safer than just about any
894
other known energy source and is therefore a worthwhile area of research. Even though
895
fusion can be recreated in laboratories, a large amount of energy needs to be utilized to
896
speed nuclei up fast enough to achieve fusion. Unless the fusion device is extremely
897
efficient, it ends up taking more energy to start the fusion than the fusion actually
898
releases. California hosts the most advanced fusion experiment in the world at the
899
Lawrence Livermore National Laboratory where scientists and engineers are working
900
daily to make breakthroughs. Students could explore an interactive computer simulation
901
of the experiment where they adjust the speed at which atoms are accelerated until
902
fusion is achieved, making measurements about the amount of energy used in the
903
device and the amount of energy released by fusion.
904
Weak interaction processes (beta decay) should be introduced as changes in
905
which neutrons transform into protons or protons transform to neutrons. Beta decay
906
allows atoms to move closer to the optimal ratio of protons and neutrons, and is key to
907
understanding why all stable nuclei have roughly equal numbers of protons and
908
neutrons, with a few more neutrons as nuclei gets bigger. Protons have an electric
909
charge while neutrons are neutral and have a slightly larger mass. Conservation laws
910
dictate that the charge and extra mass cannot just appear or disappear but must come
911
from somewhere. Applying the reasoning from conservation laws, students recognize
912
that other subatomic particles like positrons and neutrinos must exist along with protons,
913
neutrons, and electrons.
914
915
While beta decay involves small changes to nuclei, sometimes the competition
between different forces within the nucleus cause it to spontaneously split apart to form
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 51 of 106
First 60-Day Public Review Draft
November 2015
916
two or more smaller nuclei. One of these smaller products is often a helium nucleus
917
composed of two protons and two neutrons. This particle is often called an alpha
918
particle, so this type of fission is referred to as alpha decay. The smaller nuclei require
919
less total binding energy, so some of that energy is converted into kinetic energy
920
causing the smaller nuclei to rapidly fly away from one another. These nuclei are also
921
usually unstable because smaller nuclei require a different ratio of protons to neutrons
922
in order to be stable than the original larger nucleus. These smaller nuclei will often
923
release even more energy either undergoing beta decay or by releasing energy by
924
gamma radiation when their component protons and neutrons rearrange to a lower
925
(more stable) energy configuration.
926
Nuclear power plants rely on the release of energy from nuclear changes in
927
uranium (and sometimes plutonium). Nuclei of these atoms are unstable and naturally
928
decay primarily by alpha, beta, and gamma decay, but this process is very slow.
929
Reactors extract most of their energy by inducing fission. This is accomplished primarily
930
by separating out uranium-235 (a nucleus with 92 protons and 143 neutrons) from other
931
forms of uranium with different numbers of neutrons. These other forms of uranium
932
absorb neutrons, which prevents the fission process from speeding up. When fission
933
occurs in one atom of this purer uranium, neutrons that are given off are likely to collide
934
with other uranium atoms and induce them to fission. As a result, energy release can
935
maintained at a rate far above the typical background level for naturally occurring
936
concentrations of uranium. This energy is used to heat water just like other
937
thermoelectric power plants. Students can use an online simulator to model the fission
938
process and can be given the challenge to adjust the simulator settings to find the
939
minimum concentration of uranium-235 required to maintain a certain energy output
940
from fission.4
4
PhET, Nuclear Fission: https://phet.colorado.edu/en/simulation/nuclear-fission
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 52 of 106
First 60-Day Public Review Draft
941
942
November 2015
Using Radioactive Decay to Understand Earth Processes
How old is the Earth? How long ago did human civilizations arrive in California?
943
How long has this boulder been exposed at the Earth’s surface? Practically any time
944
scientists want to know about the age of events older than the written historical record,
945
they turn to radioactive decay to help them find out. This section shows how students
946
can apply their model of microscopic radioactive decay to answer such real-world
947
questions. None of the PE’s related to radiometric dating require that students can
948
perform calculations of decay rates. The emphasis is instead on a qualitative model of
949
the radiometric dating process and, more importantly, on the analysis of results from
950
radiometric dating to identify patterns that provide evidence of processes shaping
951
Earth’s surface.
952
When an atom has an unstable nucleus, it will undergo decay at a random time.
953
Different elements behave differently as the number protons and neutrons in a nucleus
954
affects the probability that an atom will decay in a certain time period, but it is not
955
possible to predict when any given nucleus will decay. Science usually strives to find
956
cause and effect relationships to predict when future events will occur, but having
957
decay being largely based on fixed probabilities means that it is not sensitive to external
958
triggers (at least under most natural conditions). Scientists have learned to calibrate
959
radiometric clocks by measuring the proportion of radioactively unstable atoms (often
960
called ‘parent products’) to stable products that are produced following decay (so-called
961
‘daughter products’). In a simple system of pure uranium-235 (a nucleus with 92 protons
962
and 143 neutrons), about 50% of the atoms will have decayed after 700 million years
963
(defined as its ‘half-life’). This probability has been calculated from much shorter
964
observations of radioactive decay in laboratories. By contrast, pure carbon-14 (a
965
nucleus with 6 protons and 8 neutrons) decays at a much faster rate with 50% of the
966
atoms decaying into nitrogen-14 within just 5,730 years. Students can visualize what is
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 53 of 106
First 60-Day Public Review Draft
November 2015
967
meant by half-life using a computer simulation5 or classroom activity with pennies
968
representing individual atoms that ‘decay’ as they flip from heads to tails 6.
969
Real materials on earth rarely involve pure chunks of Uranium-235, Carbon-14,
970
or any other radioactive parent product. There are initial amounts of other types of
971
atoms, including daughter products. Additionally, the system may not be closed and a
972
portion of the daughter product may escape. Having ‘extra’ or ‘missing’ daughter
973
products would affect the calculated age, if not properly recognized. Scientists have
974
developed sophisticated tests involving comparisons of multiple parent-daughter
975
systems to account for these issues and ensure accurate date measurements.
976
Scientists use these radiometric clocks to calculate the age of natural materials
977
and learn about the past. For example, scientists have dated meteorites that have
978
crashed into Earth’s surface. These objects have compositions similar to what we
979
expect the core of the Earth to look like, and are therefore interpreted to be pieces of
980
other planetary objects that formed around the same time as our core. Many of these
981
meteorites have similar ages of around 4.5-4.6 billion years and none have been found
982
with ages older than that. Ages on the Moon are also similar, though a bit younger (4.4-
983
4.5 billion years old). Students can use all this information as evidence for making a
984
claim about the age of Earth itself and use information about the age of the Moon to
985
construct an account of the timing and possible mechanism by which it formed (HS-
5
PhET, Radioactive Dating Game: https://phet.colorado.edu/en/simulation/radioactive-
dating-game
6
Center for Nuclear Science and Technology Information of the American Nuclear
Society, Half-Life : Paper, M&M’s, Pennies, or Puzzle Pieces:
http://www.nuclearconnect.org/in-the-classroom/for-teachers/half-life-of-paper-mmspennies-or-puzzle-pieces
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 54 of 106
First 60-Day Public Review Draft
November 2015
986
ESS1-6). A detailed assessment task for this PE was written by the authors of NGSS as
987
a model of how the 3-dimensional learning appears in the classroom7.
988
Since Earth formed, its surface has been constantly reshaped. We know this, in
989
part, due to evidence from radiometric dating. Plate tectonics is one process that
990
actively moves and deforms rocks, and students analyzed a range of data types
991
supporting this theory at the middle grade level (MS-ESS2-3). Now, students evaluate
992
the theory to see if it is consistent with evidence from rock ages calculated using
993
radiometric dating.
The oldest individual minerals in some of Earth’s oldest rocks are about 4.4
994
995
billion years old, though these rocks form only a tiny fraction of the planet’s surface.
996
Few rock formations are older than even 3 billion years, and those rocks are only found
997
on the continents. The spatial distribution of the ages of rocks on continents has
998
complicated patterns. For example, some of the oldest rocks in California are located
999
just outside the Los Angeles area in the San Gabriel Mountains. They formed 1.8 billion
1000
years ago, they are literally touching rocks just 85 million years old, and with rocks with
1001
a range of ages in between are all located within the same mountain range. This jumble
1002
of ages is evidence of California’s complicated geologic history where faults slice up
1003
rock formations and move them across the state. Some might be surprised to find that
1004
the rest of the US does not appear that much different (Figure 8). In fact, all continents
1005
show evidence of very complicated geologic histories where rocks of very different ages
1006
are mixed as continents are built up by the collision of smaller pieces and then broken
1007
back apart by later episodes of motion in a different direction.
1008
Measurements of the seafloor age, however, are much younger (no rock being
1009
older than 280 million) years and show a clear pattern. We know that there must have
1010
been oceans older than 280 million years ago because we have found fossil marine
1011
creatures in rocks currently attached to continents that date back much older than that.
7
Achieve, Unraveling Earth’s Early History — High School Sample Classroom Task:
http://www.nextgenscience.org/sites/ngss/files/HS-ESS_EarlyEarth_version2.pdf
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 55 of 106
First 60-Day Public Review Draft
November 2015
1012
So what happened to the rest of the old seafloor? A clue comes from the fact that ages
1013
typically progress in a logical order in a symmetric pattern from the middle of the ocean
1014
outwards.
1015
1016
Figure 8. Map of rock ages in the continental US (left) and seafloor (right). Continental
1017
rocks are as old as 4 billion years and are a jumbled mix of ages. Seafloor rocks show a
1018
consistent pattern and are never older than 280 million years. (National Oceanic and
1019
Atmospheric Administration, National Centers for Environmental Information 2015)
1020
Running along the center of the ocean is a band of rock with zero age. This
1021
means that there is no accumulated daughter product from radioactive decay (above
1022
the background level). How can this be when the unstable parent isotopes are present
1023
and therefore constantly decaying into the daughter products? When rock is hot, atoms
1024
can move around relatively easily and daughter products for radioactive decay can
1025
therefore escape or equilibrate with the background concentration of that element. As a
1026
rock cools, atoms are locked into their positions in crystal lattices; this is the moment
1027
when the geologic clock starts ticking. The new crust in the center of the ocean was
1028
therefore very hot in the recent past, which is evidence that it rose up from Earth’s
1029
interior. As new crust is progressively forming, it also must move constantly away from
1030
middle of the ocean. Students can calculate the rate of this motion using the radiometric
1031
age dates. At the same time, older crust must therefore be sinking down (which would
1032
be expected as the crust becomes denser as it cools over time, and explains why there
1033
are no older seafloor ages).
1034
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 56 of 106
First 60-Day Public Review Draft
November 2015
1035
Physics - Instructional segment 5: Waves and Electromagnetic Radiation
Guiding Questions:



How do we know what is inside the Earth?
Why do people get sunburned by UV light?
How do can we transmit information over wires and wirelessly?
Science and Engineering Practices:
 Asking questions
 Using mathematics and computational thinking
 Engaging in argument from evidence
 Obtaining, evaluating and communicating information
Crosscutting concepts:






Energy and matter: Flows, cycles, and conservation
Cause & Effect
Systems & System Models
Stability & Change
Interdependence of science, engineering, and technology
Influence of science, engineering, and technology on society and the
natural world
Students who demonstrate understanding can:
HS-PS4-1. Use mathematical representations to support a claim regarding
relationships among the frequency, wavelength, and speed of
waves traveling in various media. [Clarification Statement: Examples
of data could include electromagnetic radiation traveling in a vacuum
and glass, sound waves traveling through air and water, and seismic
waves traveling through the Earth.] [Assessment Boundary: Assessment
is limited to algebraic relationships and describing those relationships
qualitatively.]
HS-PS4-3. Evaluate the claims, evidence, and reasoning behind the idea
that electromagnetic radiation can be described either by a wave
model or a particle model, and that for some situations one model
is more useful than the other. [Clarification Statement: Emphasis is on
how the experimental evidence supports the claim and how a theory is
generally modified in light of new evidence. Examples of a phenomenon
could include resonance, interference, diffraction, and photoelectric
effect.] [Assessment Boundary: Assessment does not include using
quantum theory.]
HS-PS4-4. Evaluate the validity and reliability of claims in published
materials of the effects that different frequencies of
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 57 of 106
First 60-Day Public Review Draft
November 2015
electromagnetic radiation have when absorbed by matter.
[Clarification Statement: Emphasis is on the idea that photons
associated with different frequencies of light have different energies, and
the damage to living tissue from electromagnetic radiation depends on
the energy of the radiation. Examples of published materials could
include trade books, magazines, web resources, videos, and other
passages that may reflect bias.] [Assessment Boundary: Assessment is
limited to qualitative descriptions.]
HS-PS4-5. Communicate technical information about how some
technological devices use the principles of wave behavior and
wave interactions with matter to transmit and capture information
and energy.* [Clarification Statement: Examples could include solar
cells capturing light and converting it to electricity; medical imaging; and
communications technology.] [Assessment Boundary: Assessments are
limited to qualitative information. Assessments do not include band
theory.]
HS-PS4-2. Evaluate questions about the advantages of using a digital
transmission and storage of information. [Clarification Statement:
Examples of advantages could include that digital information is stable
because it can be stored reliably in computer memory, transferred
easily, and copied and shared rapidly. Disadvantages could include
issues of easy deletion, security, and theft.]
HS-ESS2-1. Develop a model to illustrate how Earth’s internal and surface
processes operate at different spatial and temporal scales to form
continental and ocean-floor features. [Clarification Statement:
Emphasis is on how the appearance of land features (such as
mountains, valleys, and plateaus) and sea-floor features (such as
trenches, ridges, and seamounts) are a result of both constructive forces
(such as volcanism, tectonic uplift, and orogeny) and destructive
mechanisms (such as weathering, mass wasting, and coastal erosion).]
[Assessment Boundary: Assessment does not include memorization of
the details of the formation of specific geographic features of Earth’s
surface.] (expanding on ideas from Instructional segment 4)
1036
Background for Teachers and Instructional Suggestions
1037
In the previous instructional segment, students found evidence that supported
1038
the idea that massive blocks of crust are moving, sometimes diving deep into Earth’s
1039
interior. One of the main ways that we investigate Earth’s interior is through seismic
1040
waves. Before students can understand that evidence, they must first understand the
1041
basic properties of waves. Ask students if they have ever experienced a thunderstorm
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 58 of 106
First 60-Day Public Review Draft
November 2015
1042
approaching. Students may be familiar with the idea that when they see a lightning bolt,
1043
they can figure out how far away it was by counting the time until they hear a clap of
1044
thunder. How does this work? Both the light from lightning and sound from thunder are
1045
dramatic forms of energy that travel away from the storm cloud. In this instructional
1046
segment, students will learn to explain the differences between the way these energy
1047
sources travel and how fast they travel.
1048
In many physics books, light, sound and other wave phenomena are described
1049
as “ways energy is transmitted without an overall flow of matter”. Such descriptions
1050
are important for understanding such things as the transmission of energy from nuclear
1051
reactions in the Sun across space to a solar panel that generates electricity, the
1052
transmission of sound energy from a performer on stage through the air to listeners
1053
throughout an auditorium, or the violent shaking in an earthquake traveling through solid
1054
rock from its source to a nearby city. However, a second aspect of light, sound, and
1055
other wave phenomena is also important, namely that they encode information, and
1056
hence are a critical tool for how we learn about and interact with the world around us.
1057
This is true not only for our natural senses, as stressed in earlier grades, but for the
1058
tools and technologies that we build and use, both for science and for everyday
1059
communication and information storage.
1060
While students are most familiar with light and sound, each of these is
1061
representative of the two broader classes of waves: mechanical and electromagnetic.
1062
Mechanical waves propagate through a medium, deforming the substance of this
1063
medium. The deformation is reversed due to restoring forces that act within the medium.
1064
For example, sound waves in the atmosphere propagate as molecules in the air hit
1065
neighboring particles and then recoil to their original condition. These collisions prevent
1066
particles from traveling in the direction of the wave, ensuring that energy is transmitted
1067
without the movement of matter over long distances. Light is an example of the second
1068
type of waves, electromagnetic. These do not require a medium for transmission, so
1069
they can travel through empty space. Electromagnetic waves consist of periodic
1070
oscillations of electrical and magnetic fields generated by charged particles. The
1071
frequency (or conversely the wavelength) of electromagnetic waves determine the
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 59 of 106
First 60-Day Public Review Draft
November 2015
1072
properties of the waves. There is a spectrum of electromagnetic radiation including
1073
radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays
1074
and gamma rays. Radio waves exhibit the lowest frequency (longest wavelength) and
1075
energy, while gamma rays exhibit the highest frequency (shortest wavelength) and
1076
energy.
1077
The medium that waves travel through has a huge impact on the speed at which
1078
the energy travels. Even though electromagnetic waves can travel through space
1079
without a medium, their speed is also affected when they are travelling through a
1080
medium. Electromagnetic waves are temporarily absorbed and re-emitted by atoms
1081
when they flow through a medium, a process which slows the wave down depending on
1082
the composition and density of the atoms in the medium. Light travels through a
1083
diamond at less than half the speed that it travels through space. For mechanical
1084
waves, the speed dependence is more intuitive because the strength of the restoring
1085
force that allows waves to propagate through a medium depends on the stiffness of the
1086
material and its density. Stiffer materials will ‘pop back into place’ faster and therefore
1087
move energy more quickly. Seismologists can measure the amount of time it takes
1088
seismic waves to travel different distances to map out the properties of materials in
1089
Earth’s interior. In an earthquake, seismic waves spread out in all directions (see the
1090
snapshot on geometric spreading in instructional segment 2) and can be recorded all
1091
over the globe. As the waves travel through denser material, they speed up and arrive
1092
sooner. These arrival time variations can be combined for thousands of earthquakes
1093
recorded at hundreds of stations around the globe to map out the materials in Earth’s
1094
interior. These ‘seismic tomography’ maps provide evidence for plate tectonics as they
1095
reveal dense plates sinking down into the mantle. At the end of the previous
1096
instructional segment, students interpreted data from radiometric dating to discover
1097
that there is no seafloor older than 280 million years and then asked questions about
1098
where it could have gone. With seismic tomography, they can gather evidence that
1099
answers this question – it is sinking into Earth’s interior.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 60 of 106
First 60-Day Public Review Draft
November 2015
1100
1101
Figure 9. Seismic waves move faster or slower as they move through different
1102
materials. Seismologists use this fact to map out the structure of Earth's interior. This
1103
image reveals evidence of plate tectonics and California’s geologic history. The
1104
remnants of a large plate sinking beneath North America is believed to be the Farallon
1105
plate that used to subduct off the coast of California (a process that created the massive
1106
granitic rocks of the Sierra Nevada mountains).
1107
Seismic waves can also reveal information about the state of matter because
1108
they behave differently in liquids than they do in solids. Liquids flow because there is
1109
very little resistance when molecules try to slide past one another. When seismic waves
1110
involve oscillations with a sliding motion (such as transverse or shear waves called S-
1111
waves whose oscillations are perpendicular to their direction of travel), liquids do not
1112
have a force that restores the particles back to their original position and so S-waves
1113
cannot propagate. Liquids do have strong resistance to compression, so waves that
1114
move by compression and rarefaction continue to travel through liquids. When an
1115
earthquake occurs on one side of the planet, the shaking should be recorded
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 61 of 106
First 60-Day Public Review Draft
November 2015
1116
everywhere on the planet as the waves travel through the Earth. Stations on the exact
1117
opposite side of the Earth from an earthquake, however, do not record S-waves. This S-
1118
wave ‘shadow’ is evidence that there must be a small liquid layer within Earth’s core
1119
that blocks the flow of S-waves. This liquid layer of the outer core is essential for
1120
creating Earth’s magnetic field (See instructional segment 3). A pioneering female
1121
seismologist named Inge Lehmann used much more complicated evidence from
1122
seismic waves to infer the existence of yet another layer, the Earth’s inner core in 1936.
1123
While it sounds like a long time ago, Galileo discovered the first distant moons of Jupiter
1124
back in 1610, more than 300 years before anyone had the first clues about what lies in
1125
the very center of our own planet. Earth science is a young science in many ways.
1126
1127
High School Vignette
1128
Seismic waves
1129
1130
Seismologists are scientists that study the Earth using a detailed, quantitative
1131
understanding of wave propagation; they are the embodiment of integrating physical
1132
science and earth science disciplines. This vignette illustrates a lesson sequence that
1133
could be used to begin an instructional segment on waves in the Physical Universe
1134
course. Students learn ESS and PS DCIs in tandem, with an understanding of each
1135
enhancing the understanding of the other.
1136
Day 1: Observing
Days 2-3: Earthquake
Day 4 – Digital versus
earthquakes
Early Warning Systems:
analog seismic
Students observe
Longitudinal and Shear
information
recordings of seismic
Waves in the Earth
Students try to encode
waves and relate them to
Students model earthquake
seismic information using
what earthquakes feel like.
waves in a slinky and with
analog and digital methods,
their bodies to show how
finding that the digital
they could design an
method works better.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 62 of 106
First 60-Day Public Review Draft
November 2015
earthquake early warning
system.
Day 5 – Damage to
Days 6-7 – Probing
Day 8 – Probing Earth’s
structures: Frequency,
Earth’s Interior: Wave
Interior II: Seismic
Wavelength, and
velocity
Tomography
Resonance
Students measure the
Students use
Students make a model of
velocity of waves on a
measurements of seismic
a city and see how different
spring. They discover the
wave velocities to make
height buildings respond to
relationship between wave
maps of materials within
different frequency shaking.
speed and material
Earth’s interior.
properties.
1137
1138
Day 1 – Observing earthquakes
1139
The first day of the lesson, Mr. J wants to get students to realize that earthquake
1140
shaking is energy moving in waves, and that wave energy takes time to travel through
1141
the Earth just like waves take time to travel towards the beach at the ocean. He wants
1142
students to discover these ideas for themselves and has designed a data-rich inquiry-
1143
based lesson. He recognizes this lesson takes a lot more time than just providing them
1144
the answer, but he knows they will have more ‘aha moments’ if they figure it out
1145
themselves. Mr. J asks students if anyone has ever felt an earthquake. A few students
1146
raise their hands and he asks them to describe what they felt, and to specifically show
1147
him with their hands the direction that their body moved during the earthquake. Some
1148
students move their hands side to side or shake them up and down. Mr. J emphasizes
1149
the differences, but highlights that one thing everyone shares in common is that the
1150
motion repeated back and forth many times, which means that they can describe the
1151
motion with waves. He begins to build a definition of waves that they will add to
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 63 of 106
First 60-Day Public Review Draft
November 2015
1152
throughout the next few days as they lean new
1153
things.
1154
Mr. J shows a short video clip of a web
1155
camera that happened to be recording during an
1156
earthquake while a man was sitting and eating
1157
his lunch. He reacts to gentle shaking at the
1158
beginning of the earthquake several seconds
1159
before strong shaking begins. Mr. J wonders if
1160
this is always true, and tells students that
1161
sensitive seismic recording devices measure
1162
shaking at different locations all around their city.
1163
He passes out papers with measurements of a
1164
single earthquake from different locations. Mr. J
1165
makes sure that students understand the axes and what the graph represents (how fast
1166
the earth was moving and in which direction over the course of an entire minute). Each
1167
student receives the recording from a different location, but all students recognize that
1168
their location felt two pulses of shaking. Sally asks if maybe there were two
1169
earthquakes, one big and one small but just a few seconds apart. Mr. J agrees that this
1170
is a good idea and asks her to how many seconds apart the two pulses were on her
1171
recording (scale, proportion, and quantity). “The second one happened about 10
1172
seconds after the first,” she says. Mr. J asks if other students also have the second
1173
pulse 10 seconds after the first and they find that every student seems to have a
1174
different time between pulses even though they are all recording the same earthquake
1175
on the same day. Why? Students compare seismograms and notice that the amplitude
1176
of the shaking is different. Evan asks Mr. J if stations with stronger amplitude shaking
1177
are closer to the earthquake source, and Mr. J confirms that this is, in general, true. He
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 64 of 106
First 60-Day Public Review Draft
November 2015
1178
asks the students to see if there is any systematic relationship between the time
1179
difference between the pulses and how far the sensor was away from the earthquake
1180
source. Students use their phones to enter the amplitude and arrival time of the two
1181
pulses from their assigned location into a collaborative spreadsheet that Mr. J has
1182
already set up. It instantly graphs the relationship and students can see that the farther
1183
away a station is from the earthquake source, the further apart the two pulses are.
1184
Mr. J then has two student volunteers act
1185
out the famous fable of a race between the
1186
tortoise and the hare as he narrates. Seismic
1187
waves, however, never take a nap like the hare in
1188
that story. For homework, Mr. J assigns students
1189
to create a visual infographic communicating an
1190
explanation about why the two pulses of energy arrive at different times at different
1191
locations. Their examples show that the two waves travel at different speeds.
1192
1193
Days 2-3: Earthquake Early Warning Systems: Longitudinal and Shear Waves in
1194
the Earth
1195
In an earthquake, people can certainly feel waves moving back and forth and at
1196
the ocean they can see them moving towards the beach. Do these two observations
1197
relate to the same type of phenomenon? Mr. J gives a short interactive lecture about
1198
mechanical waves, adding to the definition of waves the class started on the first day.
1199
Waves are caused when a disturbance pushes or pulls a material in one direction, and
1200
a restoring force ‘pops’ the material back to its original position. It’s hard to make waves
1201
in clay because it doesn’t pop back to its original position, but a material like rubber
1202
pops back instantly. Because every action has an equal and opposite reaction, the
1203
restoring force results in a ‘new’ disturbance in the adjacent material. Energy gets
1204
transferred throughout the material by a cascade of actions and reactions. Waves travel
1205
really well across a swimming pool because water always wants to flow back to its
1206
original flat shape (driven by gravity). The idea that the material a wave travels through
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 65 of 106
First 60-Day Public Review Draft
November 2015
1207
affects its ability to travel is crucial to understanding seismic waves, and Mr. J
1208
foreshadows that they will discuss the topic a lot more in a few days.
1209
Mr. J demonstrates waves using a physical model, a toy spring stretched out
1210
across the room. He asks students why he has chosen a spring for the demo instead of
1211
a piece of rope and students quickly identify that the spring will easily want to pop back
1212
into position. He shows how disturbing the spring by pulling it in different directions
1213
causes waves to travel down the spring differently, illustrating the difference between
1214
longitudinal and shear waves8. The waves go by very quickly on the spring, so Mr. J has
1215
students stand up and use their bodies as a physical model that represent the links of a
1216
slinky to act out the particle motion of the different types of waves 9.
1217
Mr. J wants to relate these two types of waves to the seismic recordings from
1218
Day 1. He passes them out again and asks students to look more carefully at the two
1219
pulses. How are they similar and how are they different? Students offer observations
1220
from their own seismograms, including Jorge’s comment that the second pulse is
1221
stronger than the first. Like yesterday, Mr. J wants to see if there are consistent
1222
patterns across all the seismograms. He has them measure the amplitude of the two
1223
pulses and submit their results to an online form using their smartphones. The class
1224
instantly analyzes the results from a graph projected on the screen and determines that
1225
almost all the locations experienced stronger shaking during the second pulse. Why
1226
would that be?
1227
Now that Mr. J has students curious, he shows a mini-lecture: Much like a storm
1228
cloud simultaneously produces lightning and thunder, earthquake waves release energy
1229
as both of these types of waves. As the blocks of crust slide past one another, the Earth
1230
is disturbed in several different directions. Textbooks and scientists refer to these
8
IRIS, Seismic Slinky,
http://www.iris.edu/hq/inclass/video/seismic_slinky_modeling_p_and_s_waves_in_the_c
lassroom
9
IRIS, Human Wave Demonstration, http://www.iris.edu/hq/inclass/demo/human_wave
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 66 of 106
First 60-Day Public Review Draft
November 2015
1231
motions as P-waves and S-waves, and they carry different amounts of energy moving at
1232
different speeds. P-waves are longitudinal waves caused by the sudden pushing or
1233
pulling of one section of rock against another. Because rocks are very strong when you
1234
push on them, this energy moves easily through rock and P-waves travel fast and arrive
1235
first. While they arrive quickly, relatively little energy is released as pushing/pulling, so
1236
P-waves don’t do much damage even in large earthquakes. Earthquakes mostly involve
1237
the sliding of two blocks of crust past one another, so they release most of their energy
1238
in the side-to-side motion of shear waves, or S-waves. Rock is weaker in shear than it is
1239
for pushing/pulling, so S-waves move more slowly through it. S-waves arrive second,
1240
but carry the powerful punch that causes great earthquake damage. The analogy with
1241
lightning and thunder holds, you quickly see lightning several seconds before booming
1242
thunder reaches you to rattle your windows.
1243
Students will explore wave speed more in a few days, but right now Mr. J tells
1244
them that they need to remember that P-waves travel faster than S-waves, but S-waves
1245
carry more energy when they finally do arrive. The fact that every earthquake comes
1246
with its own ‘gentle’ warning (a P-wave) has allowed scientists and engineers to develop
1247
systems to provide cities with advance warning of strong shaking. Mr. J shows students
1248
a short video clip about earthquake early warning systems. The video describes how
1249
automated sensors near the source of an earthquake can send warning to distant
1250
locations. Even though seismic waves travel faster than the fastest fighter jets (upwards
1251
of 6 km/s, or 13,000 mph), digital signals travel through wires and airwaves near the
1252
speed of light and can therefore provide seconds to minutes of warning prior to the
1253
arrival of strong shaking. Mr. J takes the class outside to the sports field and has them
1254
use their bodies as a physical model of slow P-waves and fast S-waves in a kinesthetic
1255
activity that illustrates early warning (d’Alessio and Horey 2013). Japan, Mexico, and a
1256
few other locations have early warning systems in place that send signals to schools,
1257
businesses, and millions of individual people via mobile phone and other media.
1258
California is even developing its own early warning. For homework, Mr. J assigns
1259
students to watch a few short YouTube videos of early warning in action during
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 67 of 106
First 60-Day Public Review Draft
November 2015
1260
earthquakes in Japan and Mexico and assigns students to write a reflection essay about
1261
1262
1263
what they would do with a few seconds of warning before an earthquake arrived.
1264
Earthquake early warning works because information from seismic recording stations in
1265
many different locations can send their measurements to a central processing center
1266
instantly. In order to avoid costly false alarms or failing to issue a warning about a
1267
damaging earthquake, the information must be transmitted reliably. Mr. J tells students
1268
that they will develop a technique for transmitting the shaking history shown by their
1269
seismogram to the students other side of the room using a small desk lamp with a
1270
dimmer attached to it. In middle school, students obtained information about the
1271
difference between analog and digital information transmission (MS-PS4-3), and today
1272
students will compare the two (HS-PS4-2). Half of the teams will transmit the
1273
information using analog techniques (adjusting the intensity of the light using the
1274
dimmer switch in order to represent the amplitude of shaking), and half will come up
1275
with a digital encoding system (such as using morse code or binary encoding to indicate
1276
amplitude values at fixed time intervals or listing frequency, amplitude, and duration
1277
values as a individual blinks to be counted). Teams can summarize their encoding
1278
protocol before beginning transmission so that everyone knows how to interpret the
1279
signals from the light. Without seeing the original seismogram, the team on the other
1280
side of the room must draw what they think the seismogram looks like based upon the
1281
signal transmitted to them and the agreed upon protocol. Students receiving the analog
1282
signal have trouble representing the shape of the signal as the solutions drawn by
1283
different students vary dramatically. Mr. J then asks what would happen if he gave
1284
students a seismogram with an amplitude just one tenth as strong as the one that they
1285
had. With the analog signal, the light gets very dim and it would be hard for students or
1286
even a computer light sensor to detect the slight variations in the light that represent the
1287
weaker shaking. The digital signal, however, just reports smaller amplitude numbers.
1288
Digital seismic recording devices can transmit information about weak signals and
1289
strong signals whereas analog seismic recordings are only useful within a certain
Day 4 – Digital versus analog seismic information
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 68 of 106
First 60-Day Public Review Draft
November 2015
1290
amplitude range. Since earthquakes with magnitude 5 and 8 could both cause damage
1291
yet have amplitudes that differ by a factor of 1000, digital encoding is the best strategy
1292
for transmitting seismic waves. And since the information is already encoded digitally, it
1293
is easy for a computer to process it and issue an earthquake early warning if it looks like
1294
the earthquake is large enough.
1295
1296
Day 5 – Damage to structures: Frequency, Wavelength, and Resonance
1297
Mr. J starts the class off by showing a video of a life size apartment building
1298
being tested on a gigantic shake table10. Is a seven story apartment building safer or
1299
less safe than a one story house? How about a 100 story skyscraper? Mr J. tells
1300
students that they are going to simulate buildings using a much simpler physical model.
1301
They will model a city using different length rectangles of heavy paper to represent
1302
different height buildings11. They attach the rectangles to a ruler that represents the
1303
ground and attach a paperclip to the top of each building to represent air conditioners
1304
and other heavy objects on the buildings’ roofs.
1305
Mr. J then asks students which
1306
building they would rather live in during an
1307
earthquake. Different students have
1308
different ideas, so he invites everyone to
1309
shake their city. Sammy is very aggressive
1310
and shakes her city back and forth very
1311
quickly and is amazed to see that the
1312
shortest building starts moving more than
1313
the others. Roland shakes more slowly
10
World’s largest earthquake test, https://youtu.be/9X-js9gXSME
11
IRIS, Demonstrating building resonance using the simplified BOSS model,
http://www.iris.edu/hq/inclass/demo/demonstrating_building_resonance_using_the_sim
plified_boss_model
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 69 of 106
First 60-Day Public Review Draft
November 2015
1314
and sees the opposite effect with the tallest building moving more than the others. This
1315
allows Mr. J to add to the class definition of waves, adding that they can be described
1316
by the frequency at which they move back and forth. Mr. J asks the students to describe
1317
their shaking using the words frequency and amplitude instead of just saying ‘quickly’ or
1318
‘slowly.’ He asks students to do a more controlled experiment where they shake with a
1319
constant amplitude (distance their hand moves back and forth), but change the
1320
frequency of shaking (how quickly their hands moves from one extreme to the other)
1321
from a low frequency to a high frequency and watch what happens to the buildings. He
1322
then asks them a series of questions:
Mr. J’s Question
Answers by his students
What did you observe during the All the buildings shook, but different
demo?
buildings at different frequencies.
How did this compare to your
prediction?
Was there a pattern in the
shaking of the buildings?
What controlled which buildings
shook?
Therefore, if the frequency of
shaking is important can anyone
propose a relationship between
frequency of shaking and
building height?
Lets revisit our original question.
Are any of these buildings more
or less likely to be damaged or
collapse during an earthquake?
Different – I predicted that building X
would shake the most, while the
physical model showed that all buildings
responded at one point or another.
Yes, first the tallest progressing to the
smallest.
Students resort back to using terms like
how “fast”, “quickly”, or “much” they
moved their hand during the demo. Mr.
J guides students to understand that the
amplitude of the shaking was constant
with only the frequency changing.
Tall buildings shake the most at low
frequencies while shorter buildings
respond at high frequencies.
It depends on the frequency of the
seismic waves. All of them could be at
risk, depending on the frequency.
1323
1324
Mr. J returns again to the class definition of waves, adding that they have a
1325
characteristic wavelength. For waves in the ocean, the wavelength is easy to visualize
1326
as the distance between two wave troughs. The buildings in the physical model shook
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 70 of 106
First 60-Day Public Review Draft
November 2015
1327
the most when their height matched the wavelength of the waves, a phenomenon called
1328
resonance. Mr. J provides a short lecture with demos using a string to visualize
1329
resonance in standing waves. He then presents a mathematical model, the equation
1330
speed = frequency x wavelength. The students perform some simple calculations to
1331
ensure that they can plug numbers in and handle the units of this equation (HS-PS4-1).
1332
Mr. J heard stories of people looking out over a valley during a large earthquake and
1333
literally seeing the earth ripple as waves passed through. He wants to know if this is
1334
reasonable. What would seismic waves look like? At the beach, ocean waves might
1335
have crests that are 30 feet apart (wavelength = 30 ft). What about seismic waves?
1336
Students return to their adopted seismic recording and look more carefully at the
1337
shaking. Mr. J asks students to calculate the frequency of the seismic waves during the
1338
earliest shaking. They might find frequencies in the range of 1-10 Hz. Scientists can
1339
calculate the velocity of seismic waves from experiments as simple as pounding a
1340
sledge hammer against the ground and measuring how long it takes the vibrations to
1341
reach a sensor a fixed distance away. The fastest waves travel in Earth’s crust is about
1342
6,000 m/s (about 13,000 miles per hour). Knowing these two values, students calculate
1343
the wavelength. Looking across a valley a bit more than a mile across, you might be
1344
able to see 2 crests of a wave with 600 m wavelength, so it is possible to see but the
1345
waves would be much broader than most ocean waves at the beach.
1346
Mr. J next shows video clips with the results of computer simulations of famous
1347
California earthquakes12. Making detailed measurements from the computer screen,
1348
students calculate two estimates of the wave velocities: one from the distance the wave
1349
fronts traveled divided by time, and one plugging frequency and wavelength
1350
observations into the equation above. Students verify that they get the same result from
1351
each equation. They then compare these computer models to a video that visualizes
1352
ripples as they were recorded by a very sophisticated network of seismic sensors during
12
USGS, Computer Simulations of Earthquakes for Teachers:
http://earthquake.usgs.gov/regional/nca/simulations/classroom.php
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 71 of 106
First 60-Day Public Review Draft
November 2015
1353
a much smaller earthquake13. Students discover that the velocity is quite similar in the
1354
two cases, but that the frequency and wavelength differ for different size earthquakes.
1355
This motivates the next activity relating seismic wave velocities to the properties of the
1356
materials.
1357
1358
Days 6-7 – Probing Earth’s Interior I: Wave velocity
1359
Mr. J starts class with a rock and a bucket of sand on the table and asks students
1360
whether they think seismic waves could travel through either of them. Most students
1361
answer no because they don’t think that either one would pop back into place like a
1362
spring. He asks them if the two different materials respond to force differently, or “Would
1363
it hurt the same amount if you fell on the solid rock versus the soft sand?” Mr. J tells
1364
them that by the end of the day, they will hopefully understand some of the differences
1365
between the materials.
1366
Mr. J returns to the physical model of the toy spring and illustrates a few more
1367
‘example earthquakes.’ He shows gentle disturbances and big disturbances (changing
1368
‘amplitude’) and changes the amount of stretch in the spring by pulling it longer or
1369
shorter before he causes the next earthquake. Students can’t visually see any
1370
consistent patterns because the spring moves so quickly, but a student records a video
1371
of the demonstration. Groups download the video and open it in a free video analysis
1372
software14 so that they can watch it in slow motion and measure and compare the
1373
speed of the waves in several sample earthquakes. When students analyze the data,
1374
they find that the speed the waves traveled was proportional to the length of the spring
1375
as it was stretched out longer or shorter. Students are surprised to see that the
13
AGI, Watch the ground ripple in Long Beach,
http://blogs.agu.org/tremblingearth/2012/12/17/watch-the-ground-ripple-in-long-beach/
http://blogs.agu.org/tremblingearth/2012/12/17/watch-the-ground-ripple-in-long-beach/
14
Brown, D. 2015. Tracker video analysis and modeling tool, http://physlets.org/tracker/.
Accessed October 16, 2015.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 72 of 106
First 60-Day Public Review Draft
November 2015
1376
amplitude of the disturbance doesn’t make much of a difference to the wave speed. Mr.
1377
J ends class by having students write an explanation describing the factors affecting
1378
wave speeds, giving them a sentence starter to “The speed waves travel along a spring
1379
depends on ______.”
1380
Mr. J returns to class the next day to the bucket of sand and the rock on the
1381
table. He asks students to work in pairs to draw a diagram that shows how the
1382
investigation of the loose versus stretched spring might be a good model for the way
1383
seismic waves might travel differently through the two materials. Olivia and Martin make
1384
the connection to restoring forces: “the restoring force is very strong in a stretched
1385
spring. Solid rock is really hard, so maybe it is like a really tight spring.” Mr. J validates
1386
their idea, explaining that it may be difficult to imagine that solid rock can act like a
1387
spring that compresses and stretches, but if you pull it hard enough it actually will do
1388
just that. Earthquakes represent massive forces from huge blocks of the earth’s crust
1389
applying forces of an unimaginable scale, and their sudden movements are strong
1390
enough to bend the rock like fingers temporarily bent the spring. In his honors class, Mr.
1391
J has students calculate wave speeds using equations that include the density and
1392
elastic modulus of the materials.
1393
Mr. J has students open up a free computer simulation to investigate waves
1394
moving through a medium15. The simulator models the behaviors of all types of waves.
1395
While the class is thinking of them as seismic waves, they could be water, sound, or
1396
light waves. Working in groups, students have a full 10 minutes to explore the program
1397
selecting some of the preset scenarios in the program and adjusting settings. Each
1398
team will present the ‘coolest’ picture they made and have to communicate their
1399
understanding of what it shows about wave behavior. Mr. J walks around interacting
1400
with each group, encouraging them to ask questions about what will happen and then
1401
try things out. After each group shares, Mr. J draws attention to Esmerelda and Dima’s
15
Ripple Tank, http://www.falstad.com/ripple/ (available as a JAVA app, Mac, Windows,
and iOS)
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 73 of 106
First 60-Day Public Review Draft
November 2015
1402
scenario which shows what happens when waves travel through materials with different
1403
velocities. “This picture could be a slice through the Earth with different earth materials
1404
like sand on top of rock,” says Mr. J. The waves leaving the source near the top left
1405
must travel through both materials to reach the bottom right. He points out how the
1406
wavelength of the source is different as the waves travel through the two materials, and
1407
asks students to estimate which material has a faster wave velocity (HS-PS4-1).
1408
1409
1410
1411
Mr. J wants students to use their mathematical thinking to learn even more
1412
about rocks. Mr. J performs an example calculation of how long P-waves will take to
1413
travel 10 km in solid rock (just 1.7 seconds at 6,000 m/s) versus dry sand (20 seconds
1414
at 500 m/s). These differences are amazing because they allow us to determine the
1415
type of rock beneath our feet without even lifting a shovel to dig. Mr. J then presents
1416
students with measurements from a few different earthquakes recorded at different
1417
locations. The data table shows the time it takes waves to arrive at each location and
1418
the distance between that location and the earthquake source. He also provides
1419
students a table of typical wave speeds of common rock and soil materials. Mr. J asks
1420
students to analyze and interpret these data by 1) calculating the average speed of the
1421
waves; and 2) identifying the dominant rock type around the earthquake source in each
Image credit: M. d’Alessio
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 74 of 106
First 60-Day Public Review Draft
November 2015
1422
situation (supports HS-PS4-1). Scientists use this exact approach to determine the
1423
types of material present at different depths in the Earth in a way that is very similar to
1424
some medical imaging technology like X-rays and MRI’s. For homework, Mr. J assigns
1425
students a video clip that shows examples of using seismic waves to locate pockets of
1426
oil and gas, map out faults before earthquakes happen, and estimate the storage
1427
capacity of a natural groundwater aquifer. Students must choose one of these earth
1428
science applications and create a one page infographic communicating the way that
1429
technology enables scientists to learn information about the earth materials through
1430
which the waves travel (HS-PS4-5). They must illustrate the path seismic waves take
1431
through this system and the different wave speeds in the different materials.
1432
1433
Day 8 – Probing Earth’s Interior II: Seismic Tomography
1434
The next day, Mr. J tells students that they are now ready to use seismic waves
1435
to probe deep inside the Earth to strengthen their model of Earth’s interior from
1436
instructional segment 4 (HS-ESS2-1). One-half of the class plays the role of theoretical
1437
seismologists and calculates the amount of time it will take waves to travel through the
1438
planet, assuming that the waves travel at a constant speed (MATH.N-Q.1, F-BF.1). The
1439
other half of the class acts as observational seismologists and analyzes data from
1440
actual earthquakes to determine their actual travel time. When the two groups compare
1441
their results, there is a point where the data and observations begin to be noticeably
1442
different, and students are able to determine the depth corresponding to this
1443
discontinuity using simple geometry (MATH.G-CO.1, G-CO.12, G-C.5). They have now
1444
used seismic waves to discover the boundary between Earth’s mantle and outer core.
1445
The different seismic wave speeds they observe reflect different densities that promote
1446
convection in Earth’s mantle (causing plate tectonics) and outer core (causing Earth’s
1447
magnetic field that protects the surface from damaging radiation in the solar wind
1448
ultimately allowing life to flourish) (HS-ESS2-1). (Adapted from DLESE Teaching Boxes
1449
2015)
1450
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 75 of 106
First 60-Day Public Review Draft
November 2015
Performance Expectations
HS-PS4-1 Waves and Their Applications in Technologies for Information
Transfer
Use mathematical representations to support a claim regarding relationships among
the frequency, wavelength, and speed of waves traveling in various media.
HS-PS4-5 Waves and Their Applications in Technologies for Information
Transfer
Communicate technical information about how some technological devices use the
principles of wave behavior and wave interactions with matter to transmit and capture
information and energy.*
HS-PS4-2 Waves and Their Applications in Technologies for Information
Transfer
Evaluate questions about the advantages of using a digital transmission and storage
of information.
HS-ESS2-1 Earth’s Systems
Develop a model to illustrate how Earth’s internal and surface processes operate at
different spatial and temporal scales to form continental and ocean-floor features.
Science and engineering
practices
Disciplinary core ideas
Developing and Using Models
PS4.A Wave Properties
Planning and Carrying Out
Investigations
PS4.C Information
Technologies and
Instrumentation
Analyzing and Interpreting
Data
Obtaining, Evaluating, and
Communicating Information
ESS2.B: Plate Tectonics and
Large-Scale System
Interactions
ESS3.A Natural Resources
ESS3.B Natural Hazards
Crosscutting concepts
Scale, Proportion, and
Quantity
Patterns
Influence of Science,
Engineering, and Technology
on Society and the Natural
World
Science Addresses Questions
About the Natural and Material
World
Connections to the CA CCSSM: MATH.N-Q.1, F-BF.1, MATH.G-CO.1, G-CO.12, GC.5
Connections to CA CCSS for ELA/Literacy:
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 76 of 106
First 60-Day Public Review Draft
November 2015
Connection to CA ELD Standards:
Connections to the CA EP & Cs: none
1451
1452
Vignette Debrief
1453
Science and engineering practices. The practice of developing and using models is a
1454
key focus throughout the vignette. Some of the models are physical (the toy spring on
1455
Days 2-3 & 6-8, and the two kinesthetic activities during Days 2-3), some are
1456
mathematical (the movement of waves through materials at different speeds on Days 6-
1457
7 and 8 and the relationship between frequency, wavelength, and velocity on Day 5),
1458
some are pictorial (like the model of Earth’s interior developed on Day 8), and some are
1459
mental models based on analogy (like the tortoise and hare fable from Day 1 and the
1460
lightning and thunder analogy on Days 2-3). Students also engage in mathematical
1461
thinking throughout the activity to answer fundamental questions such as which
1462
frequency seismic waves will damage buildings the most on Day 5 and which earth
1463
materials did waves travel through through on Days 6-7 and 8. Mr. J intentionally
1464
allowed the students unstructured exploration of the ripple tank simulator on Days 6-7 to
1465
allow them to engage in asking questions. It would have been quicker to direct
1466
students to a specific scenario within the simulator, but allowing them free reign to
1467
investigate questions that interest them gives them a crucial baseline understanding of
1468
what the simulator actually represents. It could also be the jumping off point for more
1469
detailed investigations into other aspects of wave behavior. The simulator allows for
1470
qualitative investigations, but the students also do more detailed investigations into the
1471
velocity of waves on the spring using frame-by-frame video analysis during Days 6-7.
1472
They have several instances where they briefly collect data from seismograms so that it
1473
can be analyzed, usually using their smartphones or other technology to submit their
1474
data so that the whole class can see patterns instantly. The PE’s pertaining to waves
1475
do not emphasize scientific argument or explanation, but communicating
1476
understanding is accomplished specifically using the concept of infographics on Day 1
1477
and again on Days 6-7.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 77 of 106
First 60-Day Public Review Draft
November 2015
1478
1479
Disciplinary core ideas. The vignette uses an earth science phenomenon (earthquakes)
1480
to motivate detailed understanding of a physical science concept (waves). The
1481
relationship is not one way – the physical understanding enhances understanding of the
1482
Earth science phenomena, especially on Days 2-3 where an understanding of the
1483
nature of longitudinal and shear waves allows students to explain the strength and
1484
timing of the two pulses of shaking and on the last day where understanding wave
1485
velocities allow students to probe the interior of the Earth. Seismic recording devices
1486
are a key technology discussed throughout the instructional segment, and there is
1487
explicit attention to how these systems are engineered during the discussion of new
1488
earthquake early warning systems on Days 2-3 and the digital transmission of seismic
1489
data on Day 4. The concept of earthquake engineering is briefly introduced on Day 5,
1490
but would ideally be extended to include a full engineering design activity involving a
1491
shake table that integrate concepts of forces and motion with wave resonance. Both
1492
earthquake early warning and earthquake engineering are key concepts where science
1493
and engineering can benefit society by saving lives. Technology tools such as frame-by-
1494
frame video analysis and computer simulations allow students to visualize the physical
1495
systems in ways that would not be possible without technology.
1496
1497
Crosscutting concepts. Waves themselves are examples of repeating patterns of
1498
motion. At several times during the vignette, students made observations and were then
1499
asked to quantify them (the time between arrival of different pulses on Day 1, the
1500
amplitude of those pulses on Days 2-3, and the velocity of waves during Days 6-8). Not
1501
only did this help establish the quantity, but patterns in these measurements revealed
1502
proportional relationships in two cases: the time between earthquake waves was
1503
directly proportional to their distance from the earthquake source (Day 1) and the speed
1504
of waves was directly proportional to the tension from stretching in the spring (Days 6-
1505
8).
1506
Resources for the Vignette
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 78 of 106
First 60-Day Public Review Draft
1507
1508

1509

1510
1511

November 2015
California State University Northridge. 2015. Earthquake Early Warning
Simulator. http://www.csun.edu/quake (accessed November 3, 2015).
Rapid Earthquake Viewer. 2015. http://rev.seis.sc.edu/ (accessed November
3, 2015).
1512
1513
1514
Students extend the mathematical representation of waves they made at the
1515
middle grade level (MS-PS4-1) to include the velocity of waves. Students must
1516
understand frequency, wavelength, and speed of waves, and understand the
1517
relationship between them (HS-PS4-1). For example, students should be able to
1518
evaluate the claim that doubling the frequency of a wave is accomplished by halving its
1519
wavelength. To evaluate such claims, students should be able to basic mathematical
1520
models of waves such as v = ƒλ (where v=wave velocity, f=frequency, and
1521
λ=wavelength), given that f=1/T (where T=the period of the wave). Students should be
1522
able to solve for frequency, wavelength or velocity given any of the other two variables.
1523
It is important that students realize that the equation for periodic waves is applicable to
1524
both mechanical and electromagnetic waves in a variety of media.
1525
The Nature of Light
1526
Students can also relate the mathematical representations of amplitude and
1527
frequency to electromagnetic waves by comparing light bulbs with different wattage and
1528
color temperature (e.g., packages labeled “soft white” versus “daylight”). Knowing that
1529
the wavelength of light changes its color, students are ready to learn more about the
1530
range of different frequencies of radiation in the electromagnetic spectrum.
1531
Electromagnetic radiation is an energy form composed of oscillating electric and
1532
magnetic fields that propagates at the speed of light. Electromagnetic radiation has a
1533
myriad of uses that are determined by its specific frequency and energy (Figure 10),
1534
with different ranges of frequencies given different names. Some examples of the many
1535
uses include: gamma radiation is used to kill cancer cells in radiation therapy, X-rays
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 79 of 106
First 60-Day Public Review Draft
November 2015
1536
are used to create noninvasive medical imagery, ultra-violet light is used to sterilize
1537
equipment, visible light is used for photography, infrared light is used for night vision,
1538
microwaves are used for cooking and radio waves are used for communication. Plants
1539
capture visible electromagnetic radiation (sunlight) and use the energy to fix carbon into
1540
simple sugars that subsequently provides food for all heterotrophic organisms.
1541
1542
1543
Figure 10. As students learn the physics of electromagnetic radiation, they also should
1544
learn the variety of applications that improve our quality of life. (Lightsources 2015)
1545
Even though electromagnetic radiation can clearly be described using waves and
1546
its behavior in most situations can be predicted using this model, over the years
1547
scientists have discovered certain cases where light acts more like collection of discrete
1548
particles than a wave. Students obtain, evaluate, and communicate information
1549
pertaining to the wave/particle duality of electromagnetic radiation, which has been one
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 80 of 106
First 60-Day Public Review Draft
November 2015
1550
of the great paradoxes in science (HS-PS4-3). As early as the 17th century, Christiaan
1551
Huygens proposed that light travels as a wave, while Isaac Newton proposed that it
1552
traveled as particles. This apparent paradox ultimately led to a complete rethinking of
1553
the nature of matter and energy. Taken together, the work of Max Planck, Albert
1554
Einstein, Louis de Broglie, Arthur Compton and Niels Bohr and many others suggests
1555
all particles also have a wave nature, and all waves have a particle nature. Students
1556
examine experimental evidence that supports the claim that light is a wave
1557
phenomenon, and evidence that supports the claim that light is a particle phenomenon.
1558
After analyzing and interpreting data from classic experiments on resonance,
1559
interference, diffraction and the photoelectric effect, students should be able to
1560
construct an argument defending the wave/particle model of light.
1561
One of the primary lines of evidences for the particle nature of light is the
1562
photoelectric effect, the observation that many metals emit electrons when light shines
1563
upon them. Students saw evidence of this effect in instructional segment 3 when they
1564
studied the basic principles of photovoltaic solar panels. Now, they revisit the same
1565
challenge with a new understanding of the nature of light. Thinking of light as pure
1566
waves would suggest that photoelectrons could be emitted if the amplitude of any form
1567
of electromagnetic radiation is increased sufficiently, but data shows that electrons are
1568
only dislodged if light reaches or exceeds a threshold frequency, regardless of the
1569
intensity (amplitude) of the light. This suggests that light is a collection of discrete wave
1570
packets (photons), each with energy (E) proportional to its frequency (f). Expressed
1571
algebraically, we now accept that E = hf where h is Planck’s constant (the physical
1572
constant that is the quantum of action in quantum mechanics, the discipline that deals
1573
with the mathematical description of the motion and interaction of subatomic particles.).
1574
If the energy of a photon exceeds the electron binding energy in the metal, a
1575
photoelectron will be ejected. If, however, the photon energy is insufficient, no electrons
1576
will escape, regardless of the intensity of the radiation. Thus, the energy of the emitted
1577
electrons does not depend on the intensity (amplitude) of the incident light, but only on
1578
the energy of individual photons. Electrons in the metal can absorb energy from photons
1579
when irradiated, but they follow an “all or nothing” principle in that all of the energy from
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 81 of 106
First 60-Day Public Review Draft
November 2015
1580
the photon must be absorbed to free an electron from atomic binding. If the photon
1581
energy is absorbed, some of the energy liberates the electron from the metal atom while
1582
the remainder contributes to its kinetic energy.
1583
The photoelectric effect is one example of the way that matter and
1584
electromagnetic radiation interact. As humans have become increasingly dependent on
1585
electromagnetic radiation in their everyday lives through the use of technology, their
1586
exposure to certain types of electromagnetic radiation is increasing. Many in society
1587
have asked the question about what sort of interactions there may between living tissue
1588
and radiation. Students examine claims in published materials such as websites or
1589
books and use their understanding of the nature of electromagnetic energy to evaluate
1590
the validity of those claims (HS-PS4-4). The clarification statement for this PE
1591
specifically states that the materials should be ones that are likely to contain biases, so
1592
the emphasis is on evaluating information. Teachers can build lessons that draw on
1593
existing educational resources describing how to interpret media messages and identify
1594
bias16. The key piece of scientific understanding is the model that photons of different
1595
frequency radiation have different amounts of energy (E = hf, where E is energy, h is
1596
Planck’s constant, and f is the frequency). Higher frequency radiation such as gamma
1597
rays, X-rays, and ultraviolet correspond to higher energy levels and the damaging
1598
effects of exposure to these frequencies of radiation is well documented. Students
1599
probably have even experienced it for themselves as sunburn from ultraviolet light. One
1600
way this radiation can cause damage is by breaking chemical bonds in DNA that cause
1601
mutations that lead to cancer. On the other hand, people have no concerns about being
1602
exposed to visible light from light bulbs because these photons are substantially lower
1603
energy and cause no damage. It is the intermediate energy levels of the
1604
electromagnetic spectrum where many people are asking questions about potential
1605
health-related effects, such as the microwaves used in mobile phone transmission.
16
University of California Museum of Paleontology, A scientific approach to life: A
science toolkit: http://undsci.berkeley.edu/article/sciencetoolkit_01
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 82 of 106
First 60-Day Public Review Draft
November 2015
1606
Microwaves photons are lower energy than x-rays or other high frequency radiation, so
1607
they do not have enough energy to break chemical bonds (and therefore should not
1608
cause biological damage). Students have everyday experience with this fact in that their
1609
microwave oven will heat water and even boil it away into steam, but even microwaving
1610
the water for a very long time never breaks the molecules apart into their constituent
1611
hydrogen and oxygen atoms (Do not try this at home because the steam expansion
1612
could conceivably build up enough pressure within the microwave to explode). Indeed,
1613
there are peer-reviewed studies documenting no effect of mobile phone use on cancer
1614
rates, but there are also others that show a small statistical effect. Approximately one in
1615
four Californians dies from a wide range of cancers that have a wide range of
1616
environmental causes (American Cancer Society, California Department of Public
1617
Health, California Cancer Registry 2014). Each of these people lives a different life in a
1618
different local environment, so it is extremely difficult (if not impossible) to isolate the
1619
effects of electromagnetic radiation on that cancer rate. This inability makes it difficult to
1620
make strong conclusions either way, but students should know that eventually any claim
1621
that these types of lower energy radiation cause health damage must include reasoning
1622
that explains the cause and effect mechanism (what does the radiation do to the
1623
tissue). That mechanism is well understood for high energy radiation like X-rays and
1624
has not been established for other types of radiation.
1625
Waves and Technology
1626
Waves can encode information, and technology makes use of this fact in two
1627
general ways: decoding wave interactions with mediums, and encoding our own signals
1628
on them.
1629
In some technology, we simply record waves as they travel through a medium
1630
and use our understanding of how they travel to learn about the medium itself. Medical
1631
imaging like magnetic resonance imaging (MRIs) and X-rays and are one example,
1632
while seismic recording devices that detect seismic waves are another. Both of these
1633
tools have a long history. In 1895, the German physicist, Wilhelm Röntgen, discovered
1634
a high energy, invisible form of light known as X-rays. Röntgen noticed that a
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 83 of 106
First 60-Day Public Review Draft
November 2015
1635
fluorescent screen in his laboratory began to glow when a high voltage fluorescent light
1636
was turned on, even though the fluorescent screen was blocked from the light.
1637
Roentgen hypothesized that he was dealing with a new kind of ray that could pass
1638
through some solid objects such as the screen surrounding his light. Röntgen had an
1639
engineering mind, and realized that there could be practical applications of this newly
1640
discovered form of radiation, particularly when he made an X-ray image of his wife’s
1641
hand, showing a silhouette of her bones. Röntgen immediately communicated his
1642
discovery through a paper and a presentation to the local medical society, and the field
1643
of medical imaging was born.
1644
In other technology, engineers have learned how to add waves together to
1645
encode signals on them. Italian scientist Guglielmo Marconi learned how to harness
1646
electromagnetic waves to build the first commercially successful wireless telegraphy
1647
system in 1894, harnessing radio waves to transmit information. Information can be
1648
encoded on radio waves in a variety of manners, including pulsating transmission to
1649
send Morse Code, modulating frequency in FM radio transmission, modulating
1650
amplitude in AM radio transmission, and propagating discrete pulses of voltage in digital
1651
data transmission. Students can use computer simulations or even oscilloscope apps
1652
on computers and smartphones to visualize how each of these techniques affects the
1653
shape of waveforms. Wireless transmission has revolutionized human communication
1654
and is at the heart of the Information Revolution, which is arguably one of the biggest
1655
shifts in human civilization on par with the Agricultural and Industrial Revolutions.
1656
HS-PS4-2 requires students to “evaluate questions about the advantages of
1657
using digital transmission and storage of information.” This performance objective can
1658
be met by analyzing and interpreting data regarding digital information technologies
1659
and similarly purposed analog technologies. By comparing and contrasting such
1660
features as data transmission, response to noise, flexibility, bandwidth use, power
1661
usage, error potential and applicability, students can assess the relative merits of digital
1662
and analog technologies. This PE requires students to ponder the influence of those
1663
technologies on our modern world. As students evaluate digital transmission and
1664
storage of information, they learn how scientists and engineers have applied physical
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 84 of 106
First 60-Day Public Review Draft
November 2015
1665
principles to achieve technological goals, and how the resulting technologies have
1666
gained prominence in the marketplace and have influenced society and culture.
1667
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 85 of 106
First 60-Day Public Review Draft
November 2015
1668
1669
Physics - Instructional segment 6: Stars and the Origins of the Universe
How do we know what are stars made out of?
What fuels our Sun? And will it ever run out of that fuel?
Do other stars work the same way as our Sun?
How do patterns in motion of the stars tell us about the origin of our Universe?
Crosscutting concepts:

Energy and Matter,

Patterns,

Cause and effect,

Scale, proportion, & quantity
Science & Engineering Practices:

Developing and using models

Constructing explanations
Students who demonstrate understanding can:
HS-ESS1-1. Develop a model based on evidence to illustrate the life span of the
sun and the role of nuclear fusion in the sun’s core to release energy in
the form of radiation. [Clarification Statement: Emphasis is on the energy
transfer mechanisms that allow energy from nuclear fusion in the sun’s core
to reach Earth. Examples of evidence for the model include observations of
the masses and lifetimes of other stars, as well as the ways that the sun’s
radiation varies due to sudden solar flares (“space weather”), the 11- year
sunspot cycle, and non-cyclic variations over centuries.] [Assessment
Boundary: Assessment does not include details of the atomic and sub-atomic
processes involved with the sun’s nuclear fusion.]
HS-ESS1-2. Construct an explanation of the Big Bang theory based
on astronomical evidence of light spectra, motion of distant
galaxies, and composition of matter in the universe. [Clarification
Statement: Emphasis is on the astronomical evidence of the red shift of light
from galaxies as an indication that the universe is currently expanding, the
cosmic microwave background as the remnant radiation from the Big Bang,
and the observed composition of ordinary matter of the universe, primarily
found in stars and interstellar gases (from the spectra of electromagnetic
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 86 of 106
First 60-Day Public Review Draft
November 2015
radiation from stars), which matches that predicted by the Big Bang theory
(3/4 hydrogen and 1/4 helium).]
HS-ESS1-3. Communicate scientific ideas about the way stars, over their life
cycle, produce elements. [Clarification Statement: Emphasis is on the way
nucleosynthesis, and therefore the different elements created, varies as a
function of the mass of a star and the stage of its lifetime.] [Assessment
Boundary: Details of the many different nucleosynthesis pathways for stars
of differing masses are not assessed.]
HS-ESS1-6. Apply scientific reasoning and evidence from ancient Earth
materials, meteorites, and other planetary surfaces to construct an
account of Earth’s formation and early history. [Clarification Statement:
Emphasis is on using available evidence within the solar system to
reconstruct the early history of Earth, which formed along with the rest of the
solar system 4.6 billion years ago. Examples of evidence include the
absolute ages of ancient materials (obtained by radiometric dating of
meteorites, moon rocks, and Earth’s oldest minerals), the sizes and
compositions of solar system objects, and the impact cratering record of
planetary surfaces.]
Significant Connections to California’s Environmental Principles and Concepts:
None
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
From the NGSS storyline:
High school students can examine the processes governing the formation,
evolution, and workings of the solar system and universe. Some concepts
studied are fundamental to science, such as understanding how the matter of our
world formed during the Big Bang and within the cores of stars. Others concepts
are practical, such as understanding how short-term changes in the behavior of
our sun directly affect humans. Engineering and technology play a large role here
in obtaining and analyzing the data that support the theories of the formation of
the solar system and universe. (NGSS Lead States 2013)
1680
Background for Teachers and Instructional Suggestions
1681
The Colors of Stars
1682
Students now apply their understanding of the electromagnetic spectrum to
1683
studying the light from stars. Teachers can start this instructional segment the same
1684
way humans have for millennia – looking up in the sky and wondering what is in the
1685
heavens. In a classroom, students can zoom in and out to explore the “maps” of the
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 87 of 106
First 60-Day Public Review Draft
November 2015
1686
stars and galaxies in space (such as the Sloan Digital Sky Survey17) to engender
1687
interest in what is out there, and to get a basic sense that the Universe is a varied place,
1688
with dense and less dense regions of stars and gas distributed throughout it. Students
1689
discuss and share their favorite astronomical pictures and communicate to others about
1690
what they see.
1691
1692
1693
1694
Figure 11. Color spectrum of our Sun. The rainbow image and the height of the graph
1695
depict the same information. The rainbow image is created by splitting the light from a
1696
telescope with a prism. The values of the graph are measurements of the relative
1697
intensity of each color. The graph dips lower where the rainbow image is dimmer. Image
1698
credit: (CC-BY-NC-SA) by M. d'Alessio.
1699
Looking carefully, students notice different stars have slightly different colors –
1700
those differences reveal a huge amount about what stars are and the way they work.
1701
When viewing the rainbow of light from our Sun through a prism, some colors appear
1702
brighter than others (Figure 11). What causes these variations? Are they the result of
1703
errors in the equipment, something peculiar about our Sun, or a common feature of
1704
stars? Like all good science, this general observation with the naked eye can be refined
1705
with detailed measurement of specific quantities such as the intensity of light at each
1706
wavelength. Students can collect color spectra from many different stars using an online
17
Sloan Digital Sky Survey, SDSS DR12 Navigate Tool:
http://skyserver.sdss.org/dr12/en/tools/chart/navi.aspx
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 88 of 106
First 60-Day Public Review Draft
November 2015
1707
tool18 and compare them, noticing several important patterns. These patterns give
1708
clues about the cause of different phenomena.
1709
1710
Figure 12. Comparison between the color spectra of six different. Image credit: (CC-
1711
BY-NC-SA) by M. d’Alessio with data from Sloan Digital Sky Survey 2015b
1712
Students notice that many stars have bands of low intensity at the exact same
1713
wavelength (Figure 12). Understanding this observation requires additional background
1714
in physical science. The NRC Framework lays out strong connections between the DCIs
1715
in this instructional segment and physical science:
1716
The history of the universe, and of the structures and objects within it, can be
1717
deciphered using observations of their present condition together with knowledge of
1718
physics and chemistry. (NRC Framework, p. 173)
1719
spectra from stars unites the study of matter and the study of waves. Students must
1720
build upon their understanding of matter that is too small to see (5-PS1-1) by looking at
1721
the specific make-up of atoms (HS-PS1-8). They must understand that atoms are made
18
The concept of absorption lines in
Sloan Digital Sky Survey, What is Color:
http://skyserver.sdss.org/dr1/en/proj/basic/color/whatiscolor.asp
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 89 of 106
First 60-Day Public Review Draft
November 2015
1722
of nuclei of protons and neutrons that the number of protons helps determine the
1723
physical properties of the diverse materials that make up the Universe, and that atoms
1724
have electrons that can move closer or further away from the nucleus. Understanding
1725
the evidence about light spectra requires building on the idea that light is part of the
1726
broader electromagnetic spectrum (PS4.B: HS-PS4-1). The dark bands common in star
1727
spectra occur because atoms of different elements absorb specific colors of light (Figure
1728
13). Students have studied energy conversion as early as grade four and throughout the
1729
grade spans (PS3.B: 4-PS3-4, MS-PS3-3, 4, 5, HS-PS3-3), and now they must consider
1730
a very sophisticated example of individual atoms working as tiny energy conversion
1731
devices. Atoms absorb some of the light energy that hits them (or other energy from the
1732
electromagnetic spectrum), which pushes electrons to higher energy levels than their
1733
normal “ground state,” temporarily storing the energy as a potential energy (Figure 13).
1734
The atom quickly converts the energy back to light energy to return to its ground state,
1735
but that energy may be emitted in a completely different direction than the original
1736
energy or may be at a different wavelength. Each element on the periodic table has
1737
unique electron orbitals, so different elements absorb light energy at very specific colors
1738
(wavelengths). Students can therefore use the absorption bands as ‘fingerprints’ to
1739
identify the types and relative quantity of elements in a given star. Figure 12 shows that
1740
common star spectra include fingerprints of a number of elements, and more detailed
1741
analysis allows scientists to determine the full range of elements and even their relative
1742
abundance to construct the complete chemical composition of a star’s atmosphere.
1743
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 90 of 106
First 60-Day Public Review Draft
November 2015
1744
1745
Figure 13. Absorption spectra work because individual atoms can temporarily convert
1746
light energy into potential energy. Image credit: (CC-BY-NC-SA) by M. d’Alessio with
1747
public domain images from Wikipedia and NASA.
1748
The absorption of specific wavelengths of electromagnetic waves occurs
1749
in stars, but also all around on Earth, including greenhouse gases in Earth’s
1750
atmosphere. Elements like CO2 and water vapor absorb infrared energy heading away
1751
from the planet and re-emit it back towards Earth so that energy that would have
1752
otherwise have left the system is retained. This process is fundamental to Earth’s
1753
energy balance as discussed in instructional segment 2 (HS-ESS2-4).
1754
Evidence for Fusion
1755
For ages, scientists have pondered what has caused the Sun to shine. In 1854,
1756
William Thomson (who later became so well known as a scientist that he was knighted
1757
and now is known as Lord Kelvin) published a paper calculating that the Sun would run
1758
out of fuel completely in just 8,000 years if it were made entirely of gunpowder (the most
1759
energy-dense self-contained fuel he could think of at the time) (Kelvin 1854). Even at
1760
the time, geologists had evidence that the Earth needed to be considerably older than
1761
that, so controversy ensued over what causes the Sun to shine.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 91 of 106
First 60-Day Public Review Draft
November 2015
1762
Lord Kelvin correctly determined that no chemical reaction would yield enough
1763
energy to power the Sun, but he incorrectly concluded that the Sun must be getting a
1764
constant replenishment of energy from meteors that collide with it. He died in 1907,
1765
more than a decade before scientists discovered a fuel that could release previously
1766
inconceivable amounts of energy, nuclear fusion (instructional segment 4). Under most
1767
conditions, when two atoms collide they bounce off one another because of the
1768
repulsive forces between their nuclei. If the atoms are moving fast enough, collisions
1769
can bring their nuclei enough together that they fuse, releasing more than a million
1770
times more energy per unit of mass than any chemical reaction.
1771
Students can repeat Lord Kelvin’s calculation about how long the Sun can last if
1772
it continues to emit energy at its current rate, but this time using information he didn’t
1773
have about the composition of the Sun from spectral lines (not gunpowder, but 75%
1774
hydrogen) and the energy release of hydrogen fusion (instead of chemical reactions).
1775
This approximate calculation of the scale of energy release shows that the Sun’s
1776
lifetime will be on the order of several billion years, which is consistent with what we
1777
know from radiometric dating about the age of our Solar System.
1778
A Model of Fusion in Stars Over Their Lifecycle
1779
The key to fusion is getting atoms up to a high enough temperature that they
1780
move fast enough to fuse together, typically millions of degrees. Such temperatures do
1781
not occur naturally anywhere on Earth – they only happen in the interiors of stars where
1782
temperatures and pressures are so high due to gravity and the kinetic energy of in
1783
falling matter. But even at the center of a star, conditions can change that cause fusion
1784
to start and stop. As a result, we say that stars are born and die.
1785
Stellar Birth and Activating Fusion
1786
A star begins its life as a cold cloud of dust and gas. Gravity attracts the
1787
individual dust and gas particles and they fall towards one another, decreasing the
1788
gravitational potential energy of the system. Since energy must be conserved in the
1789
system, the particles gain kinetic energy (much like a ball falling downward speeds up
1790
as it gets lower). The temperature of an object is a measure of the average kinetic
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 92 of 106
First 60-Day Public Review Draft
November 2015
1791
energy of its molecules, so we say that the star warms up as it contracts. At some point,
1792
the particles may be moving fast enough that they undergo nuclear fusion when they
1793
collide. Within the same cloud of dust and gas, many objects can form simultaneously.
1794
Objects that accumulate enough mass to start fusion are called stars. Planets are made
1795
of the exact same material as stars and accumulate by the exact same gravitational
1796
processes, but their mass is not sufficient to begin fusion.
1797
Mid-life as a Star: a Balance
1798
Once fusion begins, the energy it releases causes particles to push one another
1799
apart and the star begins to expand again. This is the opposite situation as the original
1800
star formation and involves an increase in gravitational potential energy that must be
1801
balanced by the particles slowing down (much like a ball thrown upward slows down as
1802
it gets higher). At slower speeds, fusion is less likely to occur and the star stops
1803
expanding. This balancing feedback between the explosive force of fusion and the
1804
attraction due to gravity keeps stars stable during most of their lifespan. This stable
1805
period of a star’s life is referred to as the main sequence and it means that hydrogen is
1806
fusing in the star’s core.
1807
1808
1809
Figure 14. Negative (“Balancing”) feedbacks in stars. The explosive force of fusion
1810
balances the attractive force of gravity keeping stars stable during most of their lives.
1811
Image credit: (CC-BY-NC-SA) by M. d’Alessio
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 93 of 106
First 60-Day Public Review Draft
1812
1813
November 2015
Growing older
Even the core of a young star is not typically hot enough to fuse anything except
1814
hydrogen. Larger stars burn it more quickly because they are a higher temperature, and
1815
all stars eventually fuse all the hydrogen in their core into helium, so fusion stops
1816
(marking the end of the period called the main sequence). Without fusion pushing the
1817
star outward, the balancing feedback shown in Figure 14 becomes unbalanced, and
1818
then gravity acts alone to contract star.
1819
Contraction causes temperature increases in both the core and the surrounding
1820
envelope. If the star has enough mass, it may heat enough for helium atoms to begin
1821
fusing together. If that helium gets used up, the same processes will create, in
1822
sequence, large elements up to the size of iron. Only stars that start off their lives with a
1823
large enough mass are able to generate elements larger than helium during their
1824
lifetimes. Contraction of the star’s envelope triggers hydrogen to begin fusing there. The
1825
outer envelope is less dense, so gravity does not act as effectively to hold the star
1826
together and fusion in the envelope causes the star to expand to a massive size, which
1827
is why some stars are called “giants” and “supergiants.”
1828
Our Sun is currently in its main sequence, so it has not yet been a giant and still
1829
only fuses hydrogen in its core. So how does it get all the more massive elements than
1830
helium that show up in its spectra? Where did they come from?
1831
The End of Stars
1832
Once hydrogen fusion stops in the Sun’s core, hydrogen fusion in its envelope
1833
will cause it to grow to be a giant star. Eventually its envelope will expand away and
1834
leave behind a core made primarily of carbon and oxygen. That core will still be
1835
incredibly hot and it will continue to glow for a long time even without fusion. Some of
1836
the stars we see in the night sky are actually the hot, dying cores of stars that have
1837
finished fusion.
1838
Larger stars continue fusing atoms until they end up entirely with iron in their
1839
cores and spontaneous fusion stops. The core is already very dense and gravity can
1840
cause the entire core to collapse within a few seconds. This rapid core collapse leads to
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 94 of 106
First 60-Day Public Review Draft
November 2015
1841
such high temperatures and pressures that there is finally enough extra energy to fuse
1842
elements larger than iron. Practically all of the atoms in the Universe larger than iron
1843
formed during the cataclysmic collapse of these large stars. The collapsing core
1844
rebounds in a dramatic explosion called a supernova, ejecting all of its material out into
1845
space where it can eventually coalesce into new stars. The carbon in our bodies came
1846
from carbon made in a star that exploded and was ejected into a region of space where
1847
our solar system was born. As Carl Sagan has said, “We are made of star stuff.”
1848
Students combine their model of fusion (HS-PS1-8) with the balancing feedbacks
1849
in Figure 14 to construct a model of how fusion relates to a star’s lifecycle (HS-ESS1-
1850
1). They apply this model to a product that communicates how material got from the
1851
random hydrogen atoms inside a young star to the complex range of elements inside
1852
their own bodies (HS-ESS1-3). They create a diagram, storyboard, movie, or other
1853
product that illustrates this step-by-step sequence. At each stage of their diagram, they
1854
should be able to answer the question, “What is the evidence that this particular stage
1855
happens?”
1856
1857
Snapshot: Asking Questions About Patterns in Stars
1858
Students review a table of a number of properties of the 100 nearest stars and the 100
1859
brightest stars using a spreadsheet. They construct graphs of different properties
1860
looking for patterns in this data. They find that many of the factors, are uncorrelated (“It
1861
looks like bright stars can be located both near and far from us.”), but they should see a
1862
definite pattern between brightness and temperature—hotter stars are brighter and
1863
colder stars are dimmer. They may begin with a linear scale, but with such a large
1864
range in the brightness of stars (less than 1% as bright up to 100 times brighter than the
1865
Sun), they discover will need to adjust to a logarithmic scale.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 95 of 106
First 60-Day Public Review Draft
November 2015
1866
1867
Anaya: Not all the bright stars are hot, though. Are those outliers?
1868
Cole: And not all the dim stars are cold.
1869
Ms. M.: Why do you think that is? Should we graph more data?
1870
Jordan: Maybe those dim ones are farther away.
1871
Diego: I don’t think so. We graphed distance versus brightness and there wasn’t
1872
any trend. But I’ll look specifically at the data for those stars to make sure.
1873
Jordan: Well maybe they’re smaller then. If they’re small, maybe they wouldn’t be
1874
very bright even if they were hot.
1875
1876
Anaya: And maybe those cold ones would be bright if they were really big.
1877
Students ask questions that lead them to further investigation. The example student
1878
dialog is idealized, but effective talk moves can help structure conversations so that
1879
students move towards this ideal (as outlined in the Instructional Strategies for CA
1880
NGSS Teaching and Learning in the 21st Century chapter)).
1881
This pattern in the data was discovered by Ejnar Hertzsprung and Henry Russell
1882
around 1910 and is commonly referred to as a Hertzsprung-Russell (H-R) Diagram. It
1883
appears in several different forms including color or “spectral type” instead of
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 96 of 106
First 60-Day Public Review Draft
November 2015
1884
temperature. Like the coals in a fire, cooler stars are red and hotter stars are orange,
1885
yellow, or even blue. (Several online simulations are available to allow students to
1886
explore this relationship between temperature and color.) Students can add this
1887
relationship to their model of the Sun’s energy emissions (HS-ESS1-1) because it helps
1888
explain the overall broad range of colors emitted by the Sun in Figure 11. It relates to
1889
the star’s lifecycle because most of the stars fall along the central diagonal line in the H-
1890
R diagram, which is referred to as the main sequence. As they move through their life
1891
cycle and stop fusing elements in their core, stars plot in different sections of the H-R
1892
diagram than they did during their main sequence.
1893
1894
1895
Getting Energy to Earth
As early as grade five in the CA NGSS, students generate a model showing that
1896
most of the energy that we see on Earth originated in the Sun (5-PS3-1). In
1897
instructional segment 2, students expand that model to a complete energy balance
1898
within the Earth system. Now students will expand their system model to trace the flow
1899
of energy back to fusion in the Sun’s hot core (HS-ESS1-1). Students will draw on their
1900
understanding of physical science where they conduct experiments to observe a
1901
number of processes that transfer thermal energy from hot components to cold
1902
components of a system (HS-PS3-4) such as radiation and convection. They developed
1903
a model of convection at Earth’s surface at the middle grade level (MS-ESS2-6) and in
1904
Earth’s interior in instructional segment 3, now they can apply it to the interior of the
1905
Sun. Convection occurs in a large section of the outer envelope, moving heat from the
1906
interior out to the visible surface (Figure 15). Evidence for this convection can be seen
1907
in high resolution optical images of the sun’s surface that look like a bubbling cauldron.
1908
This convection plays a role in the eruption of solar flares and other variations in solar
1909
intensity, which have been recorded for centuries (NASA 2003). Some of these
1910
variations are periodic (the Sun’s magnetic field flips about every 11 years, causing
1911
changes in the amount of radiation of about 0.1%) while slightly larger variations are
1912
less well understand but can make a big difference in Earth’s climate over much longer
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 97 of 106
First 60-Day Public Review Draft
November 2015
1913
timescales (from decades to millions of years). The existence of these variations is
1914
evidence for convection, which constantly bubbles up new high temperature material
1915
that emits more energy than the material the cooler and denser material that sinks
1916
down. Even though no fusion occurs on the visible surface, it still shines via a process
1917
known as thermal radiation (or “black body” radiation). Most of this radiation travels
1918
directly towards earth, but a small fraction of it is absorbed, creating the absorption
1919
spectra of Figure 13.
1920
1921
1922
Figure 15. Energy transfer by radiation and convection moves energy from the Sun's
1923
core to Earth. There are a number of steps along the way. Image credit: (CC-BY-NC-
1924
SA) by M. d’Alessio
1925
1926
1927
Origins of the Universe
Students will apply their skill at analyzing spectra to stars beyond the Sun. They
1928
are given examples of stellar spectra and asked to match the multiple absorption lines
1929
to a set of correctly spaced and identified lines determined in a laboratory. They find
1930
that they must shift the star spectrum as a whole to higher or lower frequency in order to
1931
match the lines from the laboratory. Understanding the significance of this observation
1932
requires understanding of the Doppler Effect, a topic that builds on physical science
1933
DCIs related to waves but is not required to meet other CA NGSS PEs. When stars
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 98 of 106
First 60-Day Public Review Draft
November 2015
1934
move towards or away from a viewer, the wavelength of their light shifts. We can
1935
therefore use the Doppler shifts to map out the movements of stars towards or away
1936
from us. For example, we find that galaxies rotate, so even if overall the galaxy is
1937
moving away from us, stars on one side of it may be less Doppler shifted than stars on
1938
the other side. When students examine different stars in different parts of the sky, they
1939
will make the discovery that almost all galaxies shifted towards longer wavelengths,
1940
revealing that they are all moving away from us. Since longer wavelengths are closer to
1941
the red end of the visible spectrum, this effect is referred to as a ‘redshift.’
Students are now ready to read or watch a historical account of Edwin Hubble’s
1942
1943
surprising discovery that the Universe is expanding (Sloan Digital Sky Survey 2015a).
1944
Hubble noticed a pattern in the redshifts: the farther away a galaxy is from Earth, the
1945
faster it moves away from us. In fact, some very distant galaxies appear from their
1946
redshift to be receding from us at greater than the speed of light, which is impossible (if
1947
they were moving that fast, their light would never reach us and we would not be able to
1948
see them). He made a model that could explain this pattern in which stars are not really
1949
moving in space, but rather the space between the stars is getting bigger (much like
1950
raisins expanding in a lump of dough). This model replaces the Doppler shift with a
1951
different explanations where the wavelengths got stretched by the stretching of space
1952
itself! Students can perform their own investigation of redshifts using simulated
1953
telescope data from online laboratory exercises19. That investigation requires an
1954
understanding of how distances are measured in the Universe, which builds on the
1955
argument students constructed in 5th grade that the apparent brightness of stars in the
1956
sky depends on their distance from Earth (5-ESS1-1). Students can work independently
19
Two older examples include Project CLEA:
http://www3.gettysburg.edu/~marschal/clea/hublab.html or University of Washington
Astronomy Department:
http://www.astro.washington.edu/courses/labs/clearinghouse/labs/HubbleLaw/hubbletitl
e.html. More modern resources could be developed.
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 99 of 106
First 60-Day Public Review Draft
November 2015
1957
or in small groups to obtain information about one of the methods for determining
1958
distance in the Universe and then combine their findings with other students to develop
1959
a report, a poster, or a presentation that describes the scale of the universe and how it
1960
is measured.
1961
Students now have evidence that the Universe is expanding, which invites them
1962
to ask questions such as, “What is causing this expansion?” and “What would the
1963
Universe look like if we could ‘rewind’ this expansion to look back in time?” The
1964
inevitable answer is that everything that we can see as far as we can look out into the
1965
Universe was all once contained in a tiny region smaller than the size of an atomic
1966
nucleus! This region was so hot and dense at this time that it effectively exploded in
1967
what we call the Big Bang. We can see evidence of this explosion in the matter and
1968
energy that exists in the Universe today. Calculations by scientists reveal that the
1969
massive explosion would produce elements in specific proportions, and we can look for
1970
that fingerprint by using spectral lines to determine the relative abundance of different
1971
elements in stars like our Sun (graph in the middle in Figure 16). While Sun’s relatively
1972
small proportion of heavier elements were formed in distant supernovas, its overall
1973
composition is similar to most other stars and matches the fingerprint predicted by the
1974
Big Bang with roughly three quarters hydrogen and one quarter helium. A hot, dense
1975
early Universe would also have emitted radiation, which should still be traveling towards
1976
us. In 1963, a group of scientists detected a constant stream of microwave radiation
1977
coming in every direction. They were worried it was something wrong with their
1978
equipment, but it became apparent that the signal they were detecting was also
1979
consistent with models of emissions of the hot early Universe. We now call that energy
1980
the Cosmic Microwave Background Radiation and can use it to get a picture of what the
1981
Universe looked like shortly after the initial Big Bang (image on the right in Figure 16).
1982
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 100 of 106
First 60-Day Public Review Draft
November 2015
1983
1984
Figure 16. Evidence of the Big Bang comes from the redshift versus distance of stellar
1985
spectra (left), the relative abundance of elements in the Sun determined from absorption
1986
spectra (middle) and the Cosmic Microwave Background Radiation that reveals minute
1987
differences in temperature in the early Universe (right). Image credit: LEFT (CC-BY-NC-
1988
SA by M. d’Alessio with data from Jha, Riess, and Kirshner 2007; MIDDLE (CC-BY-NC-
1989
SA) by M. d'Alessio with data from Lodders (2003); RIGHT NASA 2008
1990
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 101 of 106
First 60-Day Public Review Draft
1991
1992
November 2015
Works Cited
1993
1994
American Cancer Society, California Department of Public Health, California Cancer
1995
Registry. 2014. California Cancer Facts and Figures 2014. Oakland, CA: American
1996
Cancer Society, Inc. California Division.
1997
http://www.ccrcal.org/pdf/Reports/ACS_2014.pdf (accessed August 5, 2015).
1998
1999
California Energy Commission Energy Almanac. 2015. Total Electricity System Power.
2000
http://energyalmanac.ca.gov/electricity/total_system_power.html (accessed August 5,
2001
2015).
2002
2003
Center for Climate and Energy Solutions. 2015. Electricity Emissions in the United
2004
States. http://www.c2es.org/technology/overview/electricity (accessed August 5, 2015).
2005
2006
Chandigarh Traffic Police. 2015. Safety Helmets.
2007
http://www.chandigarhtrafficpolice.org/helmet.htm (accessed July 1, 2015).
2008
2009
Cinedoku Vorarlberg. 2009. Hoher Ifen Sommer Kleinwalsertal Bregenzerwald Hanno
2010
Thurnher Filmproduktion.
2011
https://commons.wikimedia.org/wiki/File:CINEDOKU_VORARLBERG_Hoher_Ifen_Som
2012
mer_Kleinwalsertal_Bregenzerwald_Hanno_Thurnher_Filmproduktion.jpg (accessed
2013
July 31, 2015).
2014
2015
Clemson University Vehicular Electronics Laboratory. 2015. Airbag Deployment
2016
Systems. http://www.cvel.clemson.edu/auto/systems/airbag_deployment.html
2017
(accessed July 1, 2015).
2018
2019
d’Alessio, M. and T. Horey. 2013. “Simulating Earthquake Early Warning Systems in the
2020
Classroom.” Science Scope 37 (4): 51–57
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 102 of 106
First 60-Day Public Review Draft
November 2015
2021
2022
DLESE Teaching Boxes. 2015. What’s THAT Inside Our Earth?
2023
http://www.teachingboxes.org/earthquakes/lessons/rev-WhatsTHAT.jsp (accessed
2024
August 5, 2015).
2025
2026
Exploratorium Teacher Institute. 2000. Eric Muller, The Squeeze Box.
2027
http://www.exo.net/~emuller/activities/The_Squeeze_Box.pdf (accessed November 3,
2028
2015).
2029
2030
Gando, A., D.A. Dwyer, R.D. McKeown, and C. Zhang. 2011. “Partial Radiogenic Heat
2031
Model for Earth Revealed by Geoneutrino Measurements.” Nature Geoscience 4 (9):
2032
647–651.
2033
2034
Grabianowski, Ed. 2008. "How Crumple
2035
ZonesWork." http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-
2036
devices/crumple-zone.htm (accessed July 31, 2015).
2037
2038
Handy, M. 2006. “Subproject G2: Controls on lithospheric deformation, erosion and
2039
plateau formation in the Central Andes inferred from thermomechanical modeling.”
2040
http://www.cms.fu-berlin.de/sfb/sfb267/projects/research_themes/g2.html (accessed
2041
October 18, 2015).
2042
2043
Herr, N. 2008. The Sourcebook for Teaching Science – Strategies, Activities, and
2044
Instructional Resources. San Francisco: Jossey-Bass.
2045
2046
Insurance Institute for Highway Safety. 2011. Small Pickups Deliver Disappointing
2047
Performances in 40 mph Crash Tests.
2048
http://www.carsafety.org/iihs/news/desktopnews/small-pickups-deliver-disappointing-
2049
performances-in-40-mph-crash-tests (accessed July 31, 2015).
2050
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 103 of 106
First 60-Day Public Review Draft
November 2015
2051
Jha, S., A.G. Riess, and R.P. Kirshner. 2007. “Improved Distances to Type Ia
2052
Supernovae with Multicolor Light-Curve Shapes: MLCS2k2.” The Astrophysical Journal
2053
659 (1).
2054
2055
Kelvin, William Thomson. 1854. “On the Mechanical Energies of the Solar System.”
2056
Transactions of the Royal Society of Edinburgh 21.
2057
http://quod.lib.umich.edu/u/umhistmath/aat1571.0002.001/24?view=image (accessed
2058
August 4, 2015).
2059
2060
Lightsources. 2015. Terahertz Radiation or T-Rays.
2061
http://www.lightsources.org/terahertz-radiation-or-t-rays (accessed July 1, 2015).
2062
2063
Lodders. 2003.
2064
2065
NASA. 2008. LAMBDA Data Products.
2066
http://lambda.gsfc.nasa.gov/product/map/dr1/max_ILC_get.cfm (accessed August 4,
2067
2015).
2068
2069
NASA. 2003. “The Inconstant Sun.” Science @ NASA. http://science.nasa.gov/science-
2070
news/science-at-nasa/2003/17jan_solcon/ (accessed August 4, 2015).
2071
2072
National Oceanic and Atmospheric Administration, National Centers for Environmental
2073
Information. 2015. Age of Oceanic Lithosphere.
2074
http://www.ngdc.noaa.gov/mgg/ocean_age/data/2008/image/age_oceanic_lith.jpg
2075
(accessed August 4, 2015).
2076
2077
National Research Council. 2012. A Framework for K–12 Science Education: Practices,
2078
Crosscutting Concepts, and Core Ideas. Washington, DC: The National Academies
2079
Press.
2080
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 104 of 106
First 60-Day Public Review Draft
November 2015
2081
NGSS Lead States. 2013. High School Physical Sciences Storyline.
2082
http://www.nextgenscience.org/sites/ngss/files/NGSS%20Combined%20Topics%2011.8
2083
.13.pdf (accessed August 5, 2015).
2084
2085
Pares Space Warp Research. 2015. The Fusion Process.
2086
http://www.paresspacewarpresearch.org/Future/Fusion.htm (accessed July 1, 2015).
2087
2088
PonderAbout. 2008. We Do Not and Can Not “Sit On” a Chair.
2089
https://www.youtube.com/watch?v=Hq3m_iS6MnA (accessed August 5, 2015).
2090
2091
Privat-Deschanel, Agustin. 1876. Elementary Treatise on Natural Philosophy, Part 3:
2092
Electricity and Magnetism. New York: D. Appleton and Co.
2093
2094
Sloan Digital Sky Survey. 2015a. The Expanding Universe.
2095
http://skyserver.sdss.org/dr1/en/astro/universe/universe.asp (accessed August 5, 2015).
2096
2097
———. 2015b. What is Color?
2098
http://skyserver.sdss.org/dr1/en/proj/basic/color/whatiscolor.asp (accessed November 3,
2099
2015).
2100
2101
Structural Tech. 2006. Pickup Truck FEM Model.
2102
https://www.youtube.com/watch?v=6vWbfKKJUD8 (accessed July 31, 2015).
2103
2104
Thomas Jefferson National Accelerator Facility - Office of Science Education. 2015.
2105
Glossary, Beta Decay.
2106
http://education.jlab.org/glossary/betadecay.html (accessed July 1, 2015).
2107
2108
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 105 of 106
First 60-Day Public Review Draft
November 2015
2109
VectorStock. 2015. Doodle Baseball Glove Vector. https://www.vectorstock.com/royalty-
2110
free-vector/doodle-baseball-glove-vector-1112699 (accessed July 1, 2015).
2111
Willet. 1999.
California Department of Education
Posted November 2015
DRAFT CA Science Framework-Chapter 7: HS Three Course Model – Physics in Universe
Page 106 of 106