To prove to your friends that air has weight, try this experiment!
1. Two latex balloons
2. A pencil or a wooden dowel
3. Three pieces of string or thread, one about two feet long, and the other two six inches each
4. Strong tape, such as duct tape
First, blow up one of the balloons. Get a parent or teacher to help you if you have trouble!
Next, tie the pencil or dowel to the two-foot piece of string such that it balances straight across—one end should not be higher than the other. Fasten the other end to the top of a door with strong tape, such that it hangs suspended in the doorway. Get a parent or teacher to help you with this, too!
REMEMBER: If the air has weight, the balloon with the air will be heavier than the balloon without air. As such, it will pull down on the end of the dowel or pencil which it is tied to.