Form cooperative learning groups of four to five children.
Distribute the balloons, bottles and bowls, to the children.
For each group, fill one bowl with hot water, and one with ice water(HAVE AN ADULT HANDLE AND CARE FOR THE HOT WATER BOWL AT ALL TIMES).
Ask one of the children from each group to fit the open end of the balloon
over the mouth of the bottle.
Instruct one child from each group to stand the bottle in the bowl filled
with hot water, as the adult holds the bowl of hot water.
Ask the children to observe what happens. (After a few minutes the
balloon will start to inflate.) Have the children share their observations.
Direct another child from each group, to move the bottle from the bowl
with the hot water to stand it in the bowl with the ice water. Ask the
children to observe what happens. (The balloon will begin to deflate after
a few minutes.) Have the children discuss what happened.
JUST IN CASE YOU PARENTS DON'T KNOW:
When air is warmed by the hot water, the molecules become more
volatile, moving around more, and requiring larger space. They stretch
out the balloon as they move further apart and cause the balloon to
become inflated. When the air is cooled the balloon deflates due to
the reduced motion of the molecules. The balloon therefore contracts.