Wax crayons, oddly enough, make good stand-ins for the different components that make up rocks. Demonstrate the way different rocks are formed, including metamorphic rocks. Use the shavings of wax crayons, some aluminum foil and a vice to show how how pressure compressing different layers of sediment, in this case the crayon shavings, from sedimentary rocks. Apply more pressure and heat from a hair dryer and watch the shavings take on a different character to show how pressure and heat change sedimentary rocks into metamorphic rocks. Apply more heat and then different methods of cooling to simulate the formation of igneous rocks.
Metamorphic rocks come in two broad categories: foliated and non-foliated, each formed under different conditions. Foliated metamorphic rocks have a striated or layered look while non-foliated metamorphic rocks lack this quality. Foliated metamorphic rocks are striated because they are formed under heat and pressure from a certain direction. Explain this difference and have students compare and contrast the look and texture of a few examples of each type of metamorphic rock.
To test students' familiarity with the qualities of different rocks try a rock identification lab. After students have an understanding of the different processes in the rock cycle, break them into groups and provide them with examples of different types of rocks. Provide them also with a key explaining the different qualities associated with each of the rock types. Challenge them to identify metamorphic, sedimentary and igneous rocks.
Metamorphic rocks are formed from pre-existing rocks getting mashed and smashed by geological forces. Teach the fifth-graders the different kinds of metamorphic rocks by helping them identify the precursor rocks they were formed from. Use examples of different metamorphic rocks and trace their stony lineage. For example, quartzite was formed from sandstone, and marble was formed from limestone.