Activity 1. Snack Tectonics
Title: Snack Tectonics
Summary: Students create a tasty model that illustrates plate tectonic motions.
year level: 5-8
Time: 15 minutes prep time and 20-30 minutes class time
Student Learning Outcomes:
•Students learn how Earth’s tectonic plates (lithosphere) ride atop the slow flowing asthenosphere layer.
•Students understand how plates interact at their boundaries.
Lesson format: Hands-on activity
National Standards Addressed:
• 5-8: Content Standard A: Science as Inquiry
• 5-8: Content Standard D: Structure of the Earth System
MATERIALS:
For each student:
•One large cracker broken in half (i.e., two square crackers)
•Two 3-inch squares (approx.) of fruit roll up
•Cup of water
•Frosting
•Sheet of wax paper
•Plastic knife or spoon
•Directions overheads ( provided below)
DIRECTIONS:
1. Make the model
a.Give each student about a square foot= 929cm of wax paper and a large dollop of frosting. Instruct students to spread frosting into a layer about half a cm thick.
b.Tell students that the frosting in this model represents the asthenosphere, the viscous layer on which Earth’s plates ride. The plates in this model are represented by fruit roll up (oceanic crust which is thin and dense) and the crackers (continental crust which is thick but less dense).
2. Divergent plate boundary
a.Instruct students to place the two squares of fruit roll up (oceanic plates) onto the frosting right next to each other.
b.Press down slowly on the fruit roll ups (because they are dense and will sink a bit into the asthenosphere) as you slowly push them apart about half a cm.
c.Notice how the frosting is exposed and pushed up where the plates are separated? This is analogous to how magma comes to the surface where real plates are moving apart at divergent plate boundaries. Most divergent plates boundaries are located within oceanic crust. When plates begin to pull apart at continents, rift valleys are made, like the great rift valley in Africa, which can become the bottom of the sea floor if the plates continue to pull apart.
3. Continental-oceanic collision
a.Instruct students to remove one of the fruit roll ups from the frosting. (They can eat it if they wish!)
b.Tell students to place one of the cracker halves lightly onto the frosting asthenosphere next to the remaining fruit roll up piece. The cracker represents continental crust, which is thicker and less dense than oceanic crust (fruit roll up). It floats high on the asthenosphere so don't push it down.
c.Gently push the continent (cracker) towards the ocean plate (fruit roll up) until the two overlap and the cracker is on top. The oceanic plate is subducted below the continental one.
4. Continent-continent collision
a.Tell students that they will next model what happens when two continents collide. Have them remove both the cracker and fruit roll up from the frosting asthenosphere. (Students can eat or discard the fruit roll up.)
b.Place one edge of both crackers into the glass of water for just a few seconds.
c.Place the crackers onto the frosting with wet edges next to each other.
d.Slowly push the crackers towards each other.
e.Notice how the wet edges crumple? This is how mountains are made at convergent plate boundaries! When continents move towards each other there is nowhere for the rock to go but up!
5. Transform plate boundaries
a.Pick the two crackers up off the frosting and turn them around so that two dry edges are next to each other.
b.Push one cracker past the other to simulate a transform plate boundary like the San Andreas fault!
6. Final step: eat all remaining model materials (except, of course, wax paper and plastic utensils!)
ASSESSMENT:
Have students draw what each situation looks like in cross section (by looking at the edge of their model)
BACKGROUND INFORMATION:
The main force that shapes our planet’s surface over long amounts of time is the movement of Earth's outer layer by the process of plate tectonics.
The rigid outer layer of the Earth, called the lithosphere, is made of plates that fit together like a jigsaw puzzle. These plates are made of rock, but the rock is, in general, lightweight compared with the denser, fluid layer underneath. This allows the plates to "float" on top of the denser material. The fluid dense material is called asthenosphere and in this activity it is represented by the frosting. However, plates are not all the same. Plates made of continental crust are thicker but less dense than plates made of ocean crust, which are denser but thinner. In this activity, ocean plates are represented by fruit roll ups and continental crust is represented by graham crackers.
Movements deep within the Earth, which carry heat from the hot interior to the cooler surface, cause the plates to move very slowly on the surface, about 2 inches per year on average. There are several different hypotheses to explain exactly how these motions allow plates to move.
Interesting things happen at the edges of plates. At divergent plate boundaries, rift valleys and spreading ridges form as plates pull away from each other. At convergent plate boundaries, where plates are coming together, subduction zones form when an oceanic plate and a continental plate collide and mountains build when two continental plates collide. Large faults form when plates slide past each other making the Earth tremble with earthquakes.
http://www.windows.ucar.edu/tour/link=/teacher_resources/teach_snacktectonics.html
The overherds to further help the children undestand the activity are orovided below
#1: Introduction, supplies needed for set-up.
#2: Divergent Plate Boundary
#3: Continent-Ocean Collision
#4: Continent-Continent Collision
#5: Transform Plate Boundary
Activity 2: Pangaea Puzzle
Type of Lesson: Hands-on activity and discussion
Time Needed: 45 minutes, or one full class period
National Standards Addressed
Earth and Space Science, Grades 5-8: The solid earth is layered with a lithosphere; hot, convecting mantle; and dense, metallic core.
Earth and Space Science, Grades 5-8: Lithospheric plates on the scales of continents and oceans constantly move at rates of centimeters per year in response to movements in the mantle. Major geological events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions.
Earth and Space Science, Grades 5-8: Some changes in the solid earth can be described as the “rock cycle.” Old rocks at the earth’s surface weather, forming sediments that are buried, then compacted, heated, and often recrystallized into new rock. Eventually, those new rocks may be brought to the surface by the forces that drive plate motions, and the rock cycle continues.
Quick Summary of LessonThis is a fun, easy way to explain plate tectonics and the various formations of the Earth's surface throughout history. It also shows why maps are distorted.
Materials
potatoes
fine tipped, permanent marker
sharp knife
student activity sheet (optional)
Procedure
1. Each group of two should start with half a potato, cut lengthwise. Now, the students should cut the potatoes into eight pieces.
2. Use the marker to write numbers on the peeling side of each piece.
3. Carefully peel away the white part of the potatoes from each puzzle piece, being sure to leave each piece of peeling in tact.
4. One of the students in the group should mix up the potato pieces and then the other student should put the puzzle back together. Then the 2 partners can switch roles.
5. Have students answer the following questions either in class discussion or have the pairs write their answers down using the Student Activity Sheet in the next section:
• Why don't the pieces fit together correctly? Which is better, a map or a globe, and why?
• Is there any significance to the numbers on each piece? Do they represent something?
• The puzzle is a good representation of the world many years ago. How would it look today? If the pieces move, what causes the movement?
• What are some phenomena that are directly related to the forces which drive the plates?
Notes to the Teacher
The resulting curved pieces will cover a greater flat space than did the hemisphere. This is an excellent illustration of the principle that the only true map is a globe; when you try to place the pieces on a flat surface, they don't fit. Gaps appear between the pieces, and if this were a map, these gaps would represent the map distortions.
Even numbers (2,4,6,8) represent Northern Hemisphere land masses. Odd numbers (1,3,5,7) represent land masses mostly in the Southern Hemisphere. Pieces 2, 4, and 6 represent Laurasia and pieces 3, 1, 5, 8, and 7 represent Gondwanaland.
The crust of the Earth including the continents is made of "plates" which are linked together like a jigsaw puzzle. These solid, but lightweight plates "float" on top of the fluid layer underneath, where the hotter magma is found. And so these plates move about 2 inches per year. Just some of the phenomena associated with the forces that drive the plates are seafloor spreading, subduction, volcanoes, faulting and earthquakes.
http://www.windows.ucar.edu/tour/link=/teacher_resources/pangaea_edu.html
below are the pictures on how to cut the potatoes
Pieces should look like this when the white part is taken off.
Africa
Eurasia
South America
North America
Antarctica
Greenland
Australia
India
http://www.windows.ucar.edu/tour/link=/teacher_resources/potatoes.html
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