Download Dynamic Earth Grade: 8th Lesson: Advance Earth - Geo

Christopher Lee Vasquez
Unit: Dynamic Earth
Grade: 8th
Lesson: Advance Earth Layered and Structure
Time: 2 periods
Standards:
NSES- Unifying Concepts and Processes (D)
HS-ESS1-5. Evaluate evidence of the past and current movement of continental and oceanic crust and the theory of plate tectonics
NCTM – Geometry and Measurement – Recognize that scientific explanations should reflect a rich scientific knowledge base, evidence of logic, higher levels of analysis, greater tolerance of criticism and uncertainty, and a clear demonstration of the relationship between logical evidence, and current knowledge.
Common Core:
MS-ESS2-2. Construct an explanation based on evidence for how geoscience processes have changed Earth’s
surface at varying time and spatial scales. Emphasis is on how processes change Earth’s surface at time and
spatial scales that can be large, slow plate motions or uplift of large mountain ranges or small such as rapid
landslides or impacts.
MS-ESS2-3. Analyze and interpret data on the distribution of fossils and rocks, continent shapes, and seafloor structures to provide evidence of the past plate motions.
Materials needed:
White Copy paper (Sequencing) (Focused Listing)
Work Sheets (Reading Strategy) (ELA) (ELL)
Brain pop video—http://www.brainpop.com/science/earthsystem/earthsstructure/ (Visual Learners)
Exit Slip Hand out
Objectives:
Students will be able to understand the differences between mechanical layers and composition layers
Students will be introduce to new vocabulary
Learning Target: I will be able to understand the differences between earths Mechanical Layers and composition layers and will be able to present this knowledge with a Depth of Knowledge exit slip.
Aim: Earth’s Layered Structure
Do Now:
What causes the wave paths to change in the diagram that the power point is showing?
(DOK 2: Skill/Concept) (BT) (Visual Learners)
Answer : The Composition of the earths layers.
Q1: One seismic wave travels straight through the center of Earth. Would this be a P-wave or an S-wave?
(DOK 1: Recall) (BT) (Visual Learners)
Answer : P-wave
Mini Lesson:
Compositional Layers
The Earth is a sphere of radius 6371km which is stratified or layered. Compositional layers differ in chemical
composition. The Earth has three compositional layers:
1. The crust: low density silicate rock, 5-70 km thick. There are two distinct types of crust.
a. Continental crust is variable in thickness and composition. Thickness ranges from 5-70 km. The composition ranges from mafic to felsic.
b. Oceanic crust is uniform in thickness and composition. It is 5-6 km thick and is mafic in composition.
c. The differences in thickness and density between continental and oceanic are responsible for the existence
of ocean basins due to isostatic balance as the crust floats on the more dense mantle.
1.
a. The mantle: high density, ultramafic silicate rock which can flow when subjected to long duration
stresses. The mantle is over 2900 km thick and makes up over 80% of the volume of the Earth. The mantle
is not molten!
b. The core: iron and nickel, liquid outer region with a solid center. The core is just over half the diameter of
the Earth.
These compositional layers have sharp or abrupt boundaries between them.
Whole earth composition is estimated from unbiased samples of meteorites. Earth structure is obtained by
combining this with seismic data.
Motion of liquid iron and nickel in the outer core gives the Earth a dipole magnetic field, nearly aligned with
the rotational axis. The magnetic field of the Earth reverses spontaneously at random times. Over the last several million years, the average time between reversals has been about 200,000 years. The last reversal was
730,000 years ago. Reversals probably take less that 5,000 years. Reversals of the field probably involve a period of time where the field weakens substantially and becomes disorganized (non-dipole), then reorganizes in
the opposite polarity. People should wear lead underwear during a reversal, as the Earth's surface will be bombarded with a higher than normal amount of cosmic radiation!
What are Earths layers based on composition? (Concept Check) (DOK) (BT)
Answer : Crust , Mantle and the Core.
Mechanical Layers
In addition to the compositional layers, the Earth has mechanical layers. Mechanical layers differ in their
strength or rigidity. These layers do not correspond on a one-to-one basis with the compositional layers. The
Earth has five mechanic layers:
1. The lithosphere is the outermost mechanical layer and is the most rigid layer of the Earth. The lithosphere
consists of the crust, and some of the uppermost mantle. The lithosphere averages about 100 km thick. It is
somewhat thicker beneath continents, and dramatically thinner under mid-ocean ridges.
2. The asthenosphere lies beneath the lithosphere. It is a part of the mantle, approximately 100 km thick,
with very little strength. The asthenosphere flows relatively easily and accomodates the movement of the
overlying lithosphere. The upper and lower boundaries of the asthenosphere are diffuse as they involve
gradual changes in the rigidity of the mantle, not a change in composition.
3. The lower mantle or mesosphere consists of most of the mantle. This part of the mantle flows, but at
much slower rates than the asthenosphere.
4. The outer core is liquid iron (with some nickel and other elements). This is the only internal layer of the
Earth that is a true liquid. The core-mantle boundary is the one mechanical boundary that is also a compositional boundary. Movement of the electrically conductive fluid in the outer core generates the Earth's
magnetic field.
The inner core is solid. It has the same composition as the outer core, and is about half the diameter of the
core.
What Part of Earth has the highest Density? (Concept Check) (DOK) (BT)
Discovering Earths Layers
Will discuss in power point how use s-waves and p-waves to discover each layer
Discovering Earths Composition
How we use rock bodies from space to give us a window to our inner and outer core.
Mini Activity :
White Copy paper (Sequencing) (Focused Listing)
Lithosphere > a._______ > b . _________ > Outer Core > ___________
Lithosphere =
Asthenosphere =
Work Sheet (Reading Strategy) (ELA) (ELL) ——worksheet is attach at end
Exit Slip- Advance Earth Layers (Four Corners DOK Exit Slip)
Describe Earths Layers based on composition
versus the earths Mechanical Layers.
(Depth of knowledge level 1) (Recall) (1 points)
List Earths Layers based on physical properties and their characteristics in order from the
Earths Center to the Surface.
(Depth of knowledge level 2) (skill/concept) (2 points)
What evidence led scientists to conclude that Earths outer core is liquid ? Explain
(Depth of knowledge level 3) (Strategic Thinking) (3 points)
Why are meteorites considered important clues to the composition of the Earths interior?
(Depth of knowledge level 4) (Extended Thinking) (4 points)