Grade Six: Plate Tectonics
Lesson 6.3: Convection Currents in the Mantle
Lesson Concept
Crust movement is the result of convection currents in the mantle.
Link
The layers of the earth from lesson 6.2 move due to convection
currents in the mantle. Lesson 6.4 demonstrates how the plates
move on top of the mantle layer.
Time
60 minutes
Materials
Whole class
H1 Convection detector (see JASON handout)
Lamp
Per Group (groups of 4)
Rectangular aluminum tray with water
3 tea candles
2 blocks or books to raise tray
One bottle of red food coloring
Two popsicle sticks
Optional Lab Materials
Bottle of vegetable oil
Bottle of dried spice (oregano, basil)
Clear Pyrex square dish
4 small pieces of rectangular Styrofoam
1 grease pencil
4 tea candles
Individual
•
H2 Convection Observation student handout
6.3 Plate Tectonics: Convection Currents in the Mantle Science Matters 1 Advance
Preparation
1. Cut out and assemble the convection detector according to the
attached directions.
2. Place materials (3 tea candles, 2 blocks of books, one bottle of
red food coloring, 2 popsicle sticks) in metal trays for
distribution.
3. Place materials (bottle of vegetable oil, dried spice, 4 small
pieces of rectangular Styrofoam, 4 tea candles) in clear Pyrex
square dish.
4. Get materials from JASON website www.jason.org
5. On the JASON website, you will need to click on
the Tectonic Fury tab on the left hand side of the
page. Then click on Mission 4: Earth on the
Move. Click on Teacher Resources, Lab #1: The
Moving Surface.
6. R1 Teacher will distribute water and light candles as indicated in
the lesson. See teacher resource.
7. Duplicate handout for observation.
Procedure:
Engage
(10 minutes) the lamp heated the air around it. The warmer,
less dense air causes the detector to spin.
Teacher Note: Set up the lamp and the convection detector for the demonstration.
1.
Ask students to observe the convection detector without the lamp underneath.
2.
Ask students to make predictions about what will happen when the convection
detector is held over the lamp. Charts predictions on the board.
3.
Ask students to observe what happens when holding the convection detector over
the lamp. Draw the movement in your notebooks.
4.
Lead a class discussion including these questions:
a. What did you observe?
b. What is the heat from the lamp doing to the air?
c. What do you think is happening when the air heats up?
d. How would you draw what was happening as the air was being heated by
the light bulb? Use colored arrows to represent the hot and cold air.
Explore
(20 minutes) The cooler more dense water will sink, pushing
the warmer less dense water above the cooler water.
6.3 Plate Tectonics: Convection Currents in the Mantle Science Matters 2 5.
Ask students to compare air and water. What is alike about air and water? What
is different between air and water?
6.
Explain that air moved our convection detector in step 3.
7.
Have students predict what will happen when a heat source is placed under a
container of water. Chart.
8.
Divide students into small groups to conduct the “Convection Currents” lab.
Distribute materials to each group including student handout. Guide students to
assemble the materials according to the picture in the teacher handout. Make sure
to line up all candles in a straight line under the center of the pan.
9.
Ask students to experiment without heat and with heat to compare the results.
Without heat, students drop one drop of food coloring into the center of the tray
and sketch and describe their observations.
10. Ask groups to empty the trays and refill them with water for the next experiment
with heat.
11. With heat, students drop one drop of food coloring into the center of the tray and
sketch and describe their observations. Record observations.
Teacher note: The candle is lit by the teacher for step 11. Students will be using the
water with the food coloring for the extend portion of the experiment. Do not have them
dump their trays.
Explain
(10 minutes) The continual pattern of heating and cooling of
the water forms convection currents.
12. Lead a class discussion including these questions:
a. How does the heat source affect how the things move in our model?
b. Which way does the water move over the heat source? Why?
c. What happens to the water when it reaches the surface? Why?
d. What happens to the water when it reaches the edge? Why?
e. Which way does it move along the bottom of the pan? Why?
f. How do you think this model relates to the earth’s mantle?
Extend
(10 minutes) The hotter, less dense mantle rises towards the
surface where it cools, becomes more dense and sinks back
toward the center of the earth. These currents slowly move the
crust around.
13. Ask students:
a. Have students predict what will happen when the popsicle sticks are
added side by side to the center of the tray.
b. What layer of the earth does the water represent?(mantle) What layer of
the earth do the popsicle sticks represent?(crust)
14. Ask students to do the experiment again with heat. Use the two popsicle sticks to
represent the plates on the crust. Observe the movement of sticks representing the
plates. Ask students to sketch the movement.
6.3 Plate Tectonics: Convection Currents in the Mantle Science Matters 3 15. Lead a discussion by asking: How might the popsicle sticks represent the plates?
How did the material move like the crust?
Evaluate
(10 minutes) Crust movement is the result of convection
currents in the mantle.
16. Have students write a short summary describing convection currents in the Earth
using the following words:
a. convection currents
b. mantle
c. crust
d. movement
e. heat
f. less dense
6.3 Plate Tectonics: Convection Currents in the Mantle Science Matters 4 H1
6.3 Plate Tectonics: Convection Currents in the Mantle Science Matters 5 6.3 Plate Tectonics: Convection Currents in the Mantle Science Matters 6