Materials Required Transparent Bottle Bowl Hot water Cold water Balloon How to do it Fill the transparent bottle with hot water. Fill the bowl with cold water. Let both the bottle and the bowl sit for one minute. Then empty out the bottle. Stretch a balloon over the mouth of the bottle. Set the bottle in the bowl of cold water. Ask the child to observe what happens with the balloon. Explanation The warm water heats the bottle first. When the water is poured out the heated bottle then heats the air inside the bottle. When the bottle is placed in the cold water, the air inside the bottle cools and contracts (gets smaller and takes up less space), causing outside air to be drawn in, pulling the balloon in and inflating it inside the bottle.
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Explanation