Name: Katherine Goepfert


Title of lesson: Edible Tectonic Plates


Length of lesson: 50 minutes


Description of the class:

                          Name of course: Science

                          Grade level: 8th

                          Honors or regular:


Source of the lesson:

               Project Earth Science: Geology, NSTA Press


TEKS addressed:

(8.1)  Scientific processes. The student conducts field and laboratory investigations using safe, environmentally appropriate, and ethical practices. The student is expected to:

(A)  demonstrate safe practices during field and laboratory investigations.

(8.2)  Scientific processes. The student uses scientific inquiry methods during field and laboratory investigations. The student is expected to:

 (B)  collect data by observing and measuring;

(C)  organize, analyze, evaluate, make inferences, and predict trends from direct and indirect evidence;

(D)  communicate valid conclusions.

(8.3)  Scientific processes. The student uses critical thinking and scientific problem solving to make informed decisions. The student is expected to:

 (C)  represent the natural world using models and identify their limitations.


(8.5)  Scientific processes. The student knows that relationships exist between science and technology. The student is expected to:

 (C)  evaluate the model and make recommendations for improving the model.

(8.14)  Science concepts. The student knows that natural events and human activities can alter Earth systems. The student is expected to:

(A)  predict land features resulting from gradual changes such as mountain building, beach erosion, land subsidence, and continental drift




I.       Overview
Students will use Milky Way TM candy bars as a model of the Earth to explore how movement of tectonic plates forms mountains, rift valleys, and oceanic trenches. 
II. Performance or learner outcomes

               Students will be able to:

Š   Model the movement of tectonic plates

Š   Predict the formation of geologic land forms due to plate movement

Š   Discuss how models can be useful tools for understanding scientific processes

III. Resources, materials and supplies needed


Š        silly putty


Š        Miniature Milky Way TM candy bars (one per student)

Š        Wax Paper

Š        Plate boundary overhead                                                                         


Š        Clear plastic container

Š        Warm water

Š        Cold water

Š        Food coloring

IV. Supplementary materials, handouts.

Š        Edible Plate Tectonics data sheet

V. Safety Considerations

Š        Check with the classroom teacher before allowing students to eat their models at the end of the lesson.

Š        Keep a close eye on boiling water.



Five-E Organization

Teacher Does                      Probing Questions                                     Student Does      


Before class starts, place corningware dish on hotplate to heat up water. 


“Scientists often look for a simple model to study how something works. When using a model, it is important to carefully observe the model’s behavior and see how accurately it reflects the real thing you are studying.”


“Sometimes we can use something common or simple to represent a much more complex concept.”


“Even though the mantle is composed of solid rocks, the mantle is hot and this makes it what we call “ductile”. This means that while they appear solid, over a long time they can slowly flow around like a liquid. We can model this behavior with silly putty.”


Bounce a ball of silly putty off the floor. 




Take silly putty and place it on an inclined surface in front of the class.


“Let’s watch this silly putty for a moment and see if it still looks like a solid.”

The silly putty will start flowing down the incline.






“The silly putty is still a solid.  When you put a force or stress on a solid for a while, the solid can actually flow like a liquid.  This is how our plates move around on a solid mantle.”

















Who can describe the layers of the earth?


Has anyone ever wondered how the continents can move around if the mantle is supposed to be solid?







What is the definition of a solid?


Would you agree that this must be a solid if it bounces?










What is happening to the silly putty?



Is the silly putty still a solid?



















Students should answer with “crust, mantle, and core.”


Students have probably never questioned this.








Students answer something with a definite shape.


Students answer yes.












Students answer that the silly putting is moving down the incline.


You will probably get mixed answers on this.







Today, we are going to use a very simple model to look at what happens when tectonic plates move around.  As scientists, one of the most important things is to make detailed observations and take good notes.  You will be given a data sheet and you need to look carefully at your model and write down what you see. 


Your model of the Earth is a Milky Way TM candy bar.




Now, as conscientious scientists, it is important that your model does not disappear before the end of the lesson.


You will work in groups of four and discuss your results and observations with your group.  This is important because our model, like the real earth, will not always behave in exactly the same way each time.


Hand out the data sheet and go over instructions and demonstrate.


You will open your “Earth Model” package and hold the candy bar upside down.


  1. Hold the candy bar with your left thumb and forefinger on one side and your right thumb and forefinger on the other side.
  2. Slowly stretch the candy bar about a centimeter. Write down a description of the surface (think of this as the Earth’s surface).
  3. Slowly push the candy bar back together until the chocolate pieces push against each other.  They may push upward, downward, or slide under one another. Write down your observations.
  4. Continue applying pressure to the candy bar by sliding the candy bar’s centers past each other like you were trying to break it. Each time describe in writing what you see on the surface.
  5. Finally, pull the candy bar completely apart and look at the exposed interior. Describe what you see by writing down your observations in the data table given. 
  6. When we are all finished, save your model’s pieces until after we discuss the results. We will dispose of the models at the end of the class.


You may begin when we bring your materials.


Can anyone tell me what plate tectonics is? 

















Can anyone make a guess as to what the candy bar is going to represent in this experiment?


































So how far do we stretch the candy bar in the first step?



































When do you get to eat the candy bar?





During exploration, ask:


Describe what is happening on the surface of the candy bar. What types of landforms do those look like?


Ensure that the students are writing down their observations as they go and not waiting for the end.


Students may answer movements of plates around the world in relation to one another and what happens along their boundaries, or something along those lines.  (If students do not get it, give definition)











Students will answer a plate or the layers of the earth.

Be sure to make clear that the correct description is a tectonic plate which includes the crust and upper mantle.































Students answer about 1 cm. 



































Students answer after we talk about what results we got.






Students will probably say that they see mountains and valleys forming.



When exploration is complete, ask the groups to describe their results. Call on groups to share their results and if they have good drawings on the data sheets, have them draw these in profile on the board.


Draw accurate diagrams on the overhead with the landforms name on them.

One diagram should be of a spreading center (divergent boundary), another should be of mountain range (convergent boundary), another is the rift valley (divergent boundary), and finally a transform fault (strike/slip fault).





Discuss results with students.




Another difference between them is that rift valleys occur inside one plate, where as mid-oceans ridges occur at two plate’s boundaries. 



















Ok students, each of the diagrams match up with your diagrams on the board; can you match them up for me?




Both rift valleys and mid-ocean ridges have spreading or stretching; what is the difference between them?

Students will describe their results.




Students will draw diagrams on board. 












Students will work together and match up their diagrams with those on the overhead. 






Students might answer that the mid-ocean is completely pulled apart where as the rift valley only gets stretched. 




Extend / Elaborate:

There is one type of plate movement we did not cover in the activity.  It is a subduction zone or trench.  Today you saw two plates of same weight (density) hitting.  




To help the students answer the question, show them a clear container with warm or room temperature water in it.  Then show them a cup of cold water with food coloring in it.



Pour the cold water into the container and watch it sink to the bottom.


So the more dense plate will go under the less dense plate.  This is subduction.


(If we have time)

Place plate boundary overhead up.


Think to your dynamic earth project.  Tell me where the ridges, mountains, trenches, and rift valleys are.  Label the different types of landforms on the map.









What would happen if one plate is less dense?







What will happen to the cold water when it is poured into the warm water?


So what would happen if two plates with different densities collide?





































Students probably won’t be able to answer this.







Students answer the cold water will sink.



Students answer the denser plate would sink.














  Pick up data tables from activity.




Students hand in data tables. 

















Edible Plate Tectonics Data Sheet






1. Pull the model apart slowly about one centimeter.



2. Push the ends back together slowly until the top surface collides.




3. Slide the sides against each other.



4. Pull the pieces completely apart and examine the interior.