Download Sample Lesson Plan Convection 2014

LESSON 4 - CONVECTION
STAGE ONE:
Lesson is designed to be taught in two 55 minute periods.
Mastery Objective of the Lesson: “By the end of the lesson students will be able to demonstrate
an understanding of how differential heating in the Earth’s interior influences the behavior of the
Earth’s crust:

Students will understand that heat from the outer core creates convection currents in the
mantle which drive most crustal processes (e.g. volcanos and earthquakes).
Language Objectives(s)
Academic Language we will use:
Crust – the outermost layer of the Earth.
Conduction - the process of transferring heat from one point to another through a solid medium.
This transfer does not involve movement of the material carrying out the process.
Continental crust – the crust that forms the Earth’s landmass composed mostly of granite.
Convection - the movement caused within a fluid by the tendency of hotter and therefore less
dense material to rise, and colder, denser material to sink under the influence of gravity, which
consequently results in transfer of heat.
Density – mass per unit volume
Oceanic crust – the crust below the Earth’s oceans consisting of a volcanic rock called basalt.
Mantle – the layer of the Earth that lies between the crust and the outer core composed of silicate
rocks that are rich in iron and magnesium.
Outer core - a liquid layer of the Earth about 1,408 miles thick composed of iron and nickel
which lies above the Earth's solid inner core and below its mantle.
Inner core - innermost part of the Earth (primarily solid ball with a radius of about 1,220 km
consisting primarily of an iron–nickel alloy.
Radiation - a method of heat transfer that does not rely upon any contact between the heat source
and the heated object. For example, we feel heat from the sun even though we are not touching
it.
Formative Assessment of student understanding: (How will you know whether the objectives
have been met?)
A series of whole class discussion will be held to gauge student understanding at multiple points
in the lesson.
Students will design their own convection cell model.
B. The Plan
Opener: How the lesson begins (10 minutes)
ENGAGE & ELICIT (prior understandings)
Teacher demonstration: turn on the lava lamp about ½ hour before the class starts. Show the
students the lava lamp and allow them to see the wax rising and sinking.
What is happening in the lava lamp? How is it like the hot air balloon? Record all student
responses for latter discussion.
The goal of this demonstration is for students to observe that when the liquid heats up it becomes
less dense and rises. This results in a transfer of heat from one area to another.
EXPLORE (45 min)
Student Competition
The focus of this lesson and this competition is on creating at convection cell. Students will be
broken into two groups and be given the following materials:
-
Styrofoam cups;
One Pyrex dish;
Food coloring;
Ice; and
Hot water
Teacher explains – The goal of this exercise is to get a circulation pattern going in a fluid (i.e.
water). Remember, nature generally wants to be in equilibrium. That means it wants everything
to be equal. For example, if one area of a container of water was hot while another area was
cold, nature would act on this system to make all of the water the same temperature. We need to
be able to follow the water as it moves to create a situation of equilibrium. Before you build your
model, I want you to think of the best way to track the movement of the water (hint: food coloring
has been provided).
I don’t want you looking this up on the internet. Just do the best you can. You can try as many
designs as you want until we are out of time. The team with the best design will be awarded first
prize.
Below is the suggested design. However, the students will be judged on how well their own
design demonstrates the concept.
EXPLAIN (20 min)
Get explanations from each group of students on why they think the food coloring moved in the
directions that it did in their explore activity. Have the groups give their ideas while the teacher
writes them on the board. Make sure not to correct any student ideas. Introduce the term
convection using the correct student ideas on the board and show students a diagram for the
interior of the Earth highlighting the mantle.
Convection - In liquids and gases, convection is usually the most efficient way to transfer heat.
Convection occurs when warmer areas of a liquid or gas rise to cooler areas in the liquid or gas.
As this happens, cooler liquid or gas takes the place of the warmer areas which have risen
higher. This cycle results in a continuous circulation pattern and heat is transferred to cooler
areas. You see convection when you boil water in a pan. The bubbles of water that rise are the
hotter parts of the water rising to the cooler area of water at the top of the pan. You have
probably heard the expression "Hot air rises and cool air falls to take its place" - this is a
description of convection in our atmosphere. Heat energy is transferred by the circulation of the
air.
Review the different relative temperatures of the interior layers as you move inside out and then
compare the magma to the food coloring.
Then introduce the topic of convection cells in the mantle as shown in the figure below.
At this time, the teacher might also link this idea to prior concepts using other convection
situations like in the atmosphere.
ELABORATE (20 min)
Setup the same convection cell experiment described above. Make a small boat out of tin foil
and set on the water near the hot water. Students should observe the behavior of the boat. Have
students go back into their groups and discuss the following questions:


Which direction does the boat move in relation to the ice and heat source? Why does it
move this way?
Based on your understanding of the different layers of the Earth, if the water represents
the mantle, what layer of the Earth does the boat represent?
The class can again meet as a group and go over these questions with the teacher to discuss their
ideas. If the students do not make the connection, the teacher should explain that the boat
represents the Earth’s crust which moves in the direction of the flowing mantle.
EVALUATE (Summative)
Quiz – Convection (see Lesson 4 – Attachment A).
EXTEND (10 min)
We know the interior of the Earth is extremely hot. It takes huge amounts of energy to keep the
outer core molten. Does anyone know where this energy comes from? Write down any student
responses and discuss.
Scientist believe there are two sources of heat in the Earth:
1. The Earth has not yet cooled down from its creation. As the Earth ages, it will lose heat
and the solid inner core will grow larger.
2. The other source of heat is the decay of radioactive isotopes of uranium, thorium and
potassium, incorporated into the Earth at its accretion. This radiogenic heat is the
principal explanation of why the Earth’s interior is still so hot after billions of years.
Without radiogenic heat the Earth would by now have cooled down to the point where the
core would probably be solid.
STAGE TWO
Connection to MA State Framework and BPS Standards:
Mass State Framework
3. Earth Processes and Cycles
Central Concepts: Earth is a dynamic interconnected system. The evolution of Earth has been
driven by interactions between the lithosphere, hydrosphere, atmosphere, and biosphere. Over
geologic time, the internal motions of Earth have continuously altered the topography and
geography of the continents and ocean basins by both constructive and destructive processes.
3.9 Explain the relationship between convection currents in Earth’s mantle and the motion of the
lithospheric plates.
How will you follow up on this lesson? (How
How have students been prepared for this
lesson (How does it connect to what they have will future lessons build on today’s work?)
done before?)
Students will have learned about the properties This lesson will be followed by the first in a
of the mantle and crust during previous
series of lectures on plate tectonics.
lectures.
Anticipated student strengths/obstacles/difficulties
Strengths – Students will have knowledge about the layers of the Earth and their properties from
earlier lectures. Weaknesses – Student may be confused by the different ways heat energy can
be transferred and how it is transferred. In addition, students will be asked to design a
convection cell using only simple materials. There may be some reluctance to this activity
because they do not have explicit instructions.
Technology
Computers
Internet access
Laboratory Safety
No laboratory exercise has been assigned for this lesson.
Differentiated instruction:
English-language learners may not be familiar with many terms used in this lesson. Thus they
will be pre-taught the academic vocabulary.
Students with learning disabilities may have trouble with some the concepts in this lesson.
Therefore, where possible visual aids will be used.
Deaf/Hard of Hearing (D/HH) students may need to lip read. Thus the teachers should always be
facing the students while lecturing and should be in good lighting.
Students who have difficulties in math will be allowed to use calculator when necessary.