- bottles with caps (same size)
- large container of water (a bathtub will do)
a) Which one weighs more?
b) What is the second bottle filled with?
2 Place both bottles in the water.
a) What happens?
3 Let some of the water out of the first bottle. Put it back in the water.
a) Now what happens? Try it with various levels of water.
4 Go through your house and find various objects. Ask yourself if they will float or sink. Then see if they do.
a) What did you notice about the things that floated?
b) Did some things that are heavy float while some things lighter than them sank?
c) Did it depend on the shape of the object?