One of the questions that the girls need to answer is "What type of rock is __________?" They've been hearing the terms "metamorphic rock" and "sedimentary rock," and I wanted them to do an activity that would give them a visual idea what these terms mean.
Using Janice VanCleave's Earth Science For Every Kid, we did two activities. The first one was called "Crunch" and the purpose is to demonstrate the formation of metamorphic rocks.
I gave Sophia and Olivia each ten toothpicks and an encyclopedia. They were instructed to snap the toothpicks in half, but leave them connected.
They piled the toothpicks on the table and then placed the encyclopedia on top of the toothpick pile.
They pressed down and removed the book.
What did this show? According to Earth Science for Every Kid, "The toothpicks flatten into layers under the pressure of the book. In nature, the weight of rocks at the surface pushes down on rock and dirt beneath, forcing them to flatten into layers. Rocks formed by great pressure are called metamorphic rock."
The second activity we did was called "Sedimentary Sandwich." This activity demonstrated a sedimentary rock formation. (It also provided part of the girls' lunch.)
They each received one slice of bread that was cut in half. They were instructed to use the knife to spread a layer of peanut butter on the slice of bread.
Then they added a layer of jelly on top of the peanut butter layer.
Then they placed the second slice of bread on top of the jelly layer and ate the sandwich.
Showing four different layers (bread, peanut butter, jam, and bread).
The book continued, "Each layer can be distinguished by differences in color, texture, and composition. The oldest layer and lowest bed is deposited first and the youngest layer is at the top. The layers over a period of time become compacted and cemented together to form solid rock structures."