This demonstration is a simple illustration of how scientists believe the earth's land masses were formed. The boiling wax and water represent the earth in its molten form.
Wax (from candles is okay)
Boil water and about 2 oz. of wax in the pan. When the wax is completely melted explain to the class that this is what the earth was like about 5 billion years ago.
Put the pan in a safe place and allow the students to observe it as it cools. What happens? (As it cools and hardens, the wax floats to the top.) Tell the children that the hardened wax represents the earth's crust.
Scientists theorize that as the planet cooled the less dense rock floated to the top and hardened, forming the earth's crust. The inner parts of the earth, the mantle and core are liquid as is the water in this demonstration.