A Metamorphic Rock Lesson So Yummy You Can Eat It!

What can be yummier than chocolate chip cookies?  Well, they are a cool metamorphic rock experiment too!  Baking cookies is a great way to observe what can happen when a rock is metamorphosed because of high heat (like contact metamorphism).

This experiment is an easy way to describe a metamorphic change to children because they can see that the raw and baked dough are the same ingredients that are changed by heat. All you need is your favorite cookie recipe. Each ingredient is a “mineral” that is mixed together with other minerals to create a cookie rock. When you expose the cookie dough to high heat in the oven, the dough turns into a metamorphic rock cookie!

You will need:

  • 1 Cup Butter, soften at room temperature
  • 3/4 Cup Granulated white sugar
  • 3/4 Cup Brown sugar, firmly packed
  • 2 large Eggs
  • 1 teaspoons Pure vanilla extract
  • 2 1/4 Cups All-purpose flour
  • 1 teaspoon Baking soda
  • 1/2 teaspoon Salt
  • 1 Cup Semisweet chocolate chips
  • 1 Cup Candy coated chocolate chips
  • 1 Cup  Chopped nuts, coarsely chopped (do not use if you have nut allergies)
  • Mixing bowl
  • Mixing spoon
  • Baking sheet
  • Cooling rack
  • Spatula

To make your “Original Rock”:

Step 1: Combine the butter, granulated sugar, brown sugar and vanilla in a bowl and beat until creamy.

Step 2: Add eggs and mix well.

Step 3: Add in flour, baking soda and salt.

Step 4: Mix in chocolate chips, candies and nuts (these are the large “minerals” and “fossils” in your rock).

Observe:

What does your rock look like?  What is the texture?

To metamorphose your rock (bake your cookies):

Place 12 spoonfuls of rock dough on a cookie sheet and bake for 8 to 11 minutes at 375 degrees until the cookies are golden brown.  Cool on baking sheet for 1 to 2 minutes then completely cool on wire rack.

Observe: What do your metamorphosed “rocks” look like?  How did the original rock change?  Did the “minerals” and “fossils” change?  If so, how did they change?

This experiment is included in our Metamorphic Mystery Rock Detectives Kit and the Rock Detective Camp Guide.

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