Geology Cupcakes

Geology Cupcakes

Developed by: Kristin Schild, PhD Candidate

Department of Earth Sciences

Adapted from: Doing What Works, and e-binder for 2013 CEETEP workshop

Geologists use rock cores as a means to determine the likely composition of rock beneath us, without having to completely clear the land. In this exercise, students will take multiple “rock” cores of a cupcake, measure and record the different rock types, calculate the age of the core, and create a stratigraphic map. Students will make connections between the abstract concept of geologic time and the physical representation of rock core layers by considering types of geological processes.

What does the stratigraphy of rock layers under our feet look like and how old are they?

Through this lesson, students will:

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  Make an informed prediction about the age of their cupcake
  
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  Perform a “rock” core extraction
  
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  Measure each section of their core and record their results
  
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  Learn that the earth is made up of various (sometimes discontinuous) layers
  
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  Predict the stratigraphy of the untouched portion of the cupcake
  
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  Use math to determine the age of each of their cores
  
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  Analyze and think critically about their results
  

The earth’s crust is made up of sedimentary, metamorphic, and igneous rocks. Different rock types are deposited in layers and then modified by two major processes: those that wear down the surface (weathering/erosion) and those that change and/or build up the surface (volcanism/tectonics). Because of these processes, sometimes dating the rocks is not as easy as just looking at the layering or determining how long a rock type took to form. In this lab the students will begin thinking about geologic time (but the “ages” are entirely arbitrary).

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  White/yellow cake mix and associated cooking ingredients
  
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  Foil cupcake wrappers
  
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  Food coloring
  
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  Candy sprinkles or shapes (optional)
  
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  Thick plastic straws (can be cut in half or thirds) – 3 per cupcake
  
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  Napkin – 1 per cupcake
  
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  Small containers of cooking oil – 1 per ~3 cupcakes
  
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  Ruler
  
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  Colored pencils
  
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  Plastic knives – a few for the class to share
  
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  Lab recording sheet (below)
  

1. 
   Prepare the cake mix (a dense mix works best) and divide batter into several bowls. Add food coloring to each bowl
   

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  Can add “fossils” by adding sprinkles or candy dinosaurs, etc. (colored sugar does NOT work, it just melts and mixes with the cake)
  
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  You will want to add plenty of food coloring to each bowl- a “white” cake layer looks the exact same as a yellow food coloring layer when baked
  

2. 
   Pour small amounts of each color into each of the foil cupcake wrappers
   

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  If not a dense mix, will want to bake a few minutes between each later
  
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  It is easiest to have the cupcakes rise just up to the layer of the foil wrappers, if not a little bit under, so only fill with batter to about half.
  

3. 
   Let cupcakes air dry (for about a day works best), then frost.
   

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  It may be easier to transport a lot of cupcakes unfrosted, and then get to school early and frost before the day begins
  

4. 
   When in the classroom, prepare a few containers of cooking oil (~1 inch deep)
   

Teacher—

2. Pass out Lab, cupcakes, napkins, straws, colored pencils and rulers. Have containers of oil on a few different tables. Keep the plastic knives for the end so the students can cut open their cupcake and compare results.

3. Read through the lab with the students (maybe before passing out the cupcakes and sampling supplies) and demonstrate the sampling technique.

4. Closure: Have the students report their findings

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  The teacher could do any sort of charting or graphing using every cupcake age in each section and then compare between different sections of the class (Which class has the oldest cupcake? Oldest cumulative cupcake ages?)
  
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  Did any students get their stratification correct? Were some completely different than expected?
  

5. 
   Closure: Can do a class discussion using any of the “extended questions” especially the real world applications- why would knowing the rock type matter for the students?
   
6. 
   Closure: no one eats the cupcake until Question #6 is answered!
   

How did they answer the questions?

Did their diagrams seem appropriate?

Could they explain how sampling is important to scientific and everyday questions?

1. Additional Questions:

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  What are the limitations of using rock core samples as a means to predict the layers under the surface?
  
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  What could be an alternative stratigraphic map than the one you drew?
  
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  Where else could cores be drilled than just on the land? (answer: Sediment cores as lakes, ocean cores, Ice cores)
  
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  Why might it be important to know the composition of rock beneath you? Name a few situations (some answers: building a house- bedrock or sedimentary rock, oil mining, fault zones, etc.)
  
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  Besides rock coring, how else could geologists determine rock layers under the surface? (answers: seismic (sound) waves, Ground Penetrating Radar, etc.)
  
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  What was going on in the world when your oldest layer (bottom) was being deposited? (e.g. dinosaurs were inhabiting the planet)
  

3. This can be modified to become an engineering exercise- assign a cost to each cm drilled and have the students decide how to best create an accurate stratigraphic map using the least amount of funds.