Download Thermal Convection

DRAFT
Hot Plates
Original Source: COASTeam, Project Oceanica, College of Charleston
Grade Level:
SC Standards:
5th and 8th Grade
National Standards:
Earth and Space Science – Content Standard D:
As a result of their activities in grades 5-8, all students should develop an
understanding of the structure of the earth system.
5th – IA2a,b; IA4a; IA6a,b; IB1d; IIIA2a,b
8th – IA1d,e; IIIB1b,c,d,e,f
Focus Question:
What causes tectonic plates to move?
Objectives: Students will
examine the circulation patterns caused by
a difference in temperature and how this
relates to the movement of the tectonic
plates.
Key Words:
Thermal Convection
Convection Current
Mantle
Viscous
Tectonic Plates
Divergent boundaries
Convergent boundaries
Materials:
One lava lamp
Two pieces of cardboard approximately the
size of a piece of paper.
Diagram of thermal convection (see
Appendix A)
Transparency of Appendix A
Preparation:
Turn the lava lamps on first thing in the morning
so they’re warmed up. Make a transparency of
Appendix A.
Time Frame:
One 50-minute class period
Suggested Learning Environment:
The students should be arranged in buzz groups
of 3-4.
Teacher Background Information:
Excerpt from “Of Sand and Sea”, p. 9-16:
It is believed that earth's outer core is mostly
liquid iron. This liquid metal is extremely hot
and flows in a known pattern called a convection
current. Convection currents are caused by the
very hot material inside the earth rising, then
cooling and sinking, then heating, rising and
repeating the cycle over again. This convection
current flows within the outer core of the earth
and brings heat to the boundary between the
core and the mantle where some of it is
transferred into the mantle. Temperatures are
hot enough in the upper mantle ( 1200 C) to
cause thermal convection of the highly viscous
upper mantle rocks, although it flows very slowly
– approximately one cm/yr. This flow is most
likely the cause of plate tectonic motions.
The heat within the earth is the ultimate
driving force for plate tectonics and mantle
convection. The thermal convection currents
are like a conveyor belt and the upwelling
pressure forces plates apart, causing them to
move in opposite directions. (see Appendix A)
Relevant pages of “Of Sand and Sea”:
Chapter I, The Ocean Planet, pp. 9,10,15 and 16.
Procedures:
Engage
1. Ask the students to observe the lava lamp
and state their observations. Which
COASTeam Program, Project Oceanica, College of Charleston
DRAFT
direction does the “lava” move? Why do you
think it moves this way?
Explain
2. Ask each student to draw his/her
observations of the lava – label and use
arrows to show lava movement.
3. Have each buzz group discuss their
observations with each other. What can you
interpret from these observations?
Explore
4. Give each group one hint about why the lava
moves the way it does: The base of the lamp
is very hot. What’s happening to the lava
because of this?
5. Have each buzz group present their
interpretations to the rest of the class.
Students should show their illustration of
the lava movements.
6. Give each group a print-out of thermal
convection (Appendix A). How does this
drawing relate to your drawing? What part
of the lava lamp represents the earth’s
core?
7. Relate this to plate tectonic activities
students have done previously, such as
“Puzzling Plates”, “Why is there
Lithosphere”, and “Quakes and Plates”.
Expand
8. The students will now model a convection
current and the divergence of two tectonic
plates. Have students hold two pieces of
cardboard (representing tectonic plates)
horizontally with their edges touching. Hold
the cardboard pieces over the top of the
lava lamp.
9. Ask a few students to come up and move the
“plate” with the lava. How do you know
which direction the “plate” moves? How
does this relate to plate tectonics in the
earth’s crust?
10. Using a transparency of Appendix A, review
with the students divergent and convergent
boundaries. How does the movement of the
lava relate to the different types of plate
boundaries?
Below are a few web sites that they can
start with:
a. http://theory.uwinnipeg.ca/mod_tech/n
ode195.html
b. http://www.lpi.usra.edu/science/kiefer/
Research/convection.html
c. http://www.eas.purdue.edu/~scott/mantle/
mantle.html
d. http://www.eas.purdue.edu/~braile/edumod
/convect/convect.htm
e. http://pubs.usgs.gov/publications/text/unan
swered.html
Assessment:
Evaluate
The accuracy of the ideas presented by the buzz
groups should be the measuring tool for the
students’ understanding of the subject.
Did they understand the relationship
between the movement of the lava in the
lamp to the movement of plates on earth?
Were they able to move the “plate” with the
lava lamp correctly?
Were the students able to work together to
record observations of the lava lamp?
Explore the Oceans, 2nd ed. is a product of the
COASTeam Program at the College of Charleston
in Charleston, SC. Funding is provided by the
South Carolina Sea Grant Consortium.
Development team members include: Jennifer
Jolly Clair, Rachel McEvers, Sarah McGuire,
Margaret Olsen, Leslie Sautter, Lundie Spence,
and Meta Van Sickle.
* “Of Sand and Sea: Teachings from the
Southeastern Shoreline” 2002 by Paula KeenerChavis and Leslie Reynolds Sautter. $7.00
Contact the South Carolina Sea Grant Consortium,
287 Meeting St., Charleston, SC 29401,
www.scseagrant.org, (843) 727-2078.
Extensions:
1.
Have the students research how thermal
convection causes tectonic plate movement.
COASTeam Program, Project Oceanica, College of Charleston
DRAFT
APPENDIX A: Thermal Convection Diagram
From “Of Sand and Sea”, pg. 16
COASTeam Program, Project Oceanica, College of Charleston