Can't have summer without lots of balloons : )
We have done a number of science activities over the last few weeks using balloons. We first discussed the theory (annotated on a white board) then went ahead with the activity when we understood the science behind it.
Balloon car races and balloon rockets
Balloon bounce (they had to keep an air filled water balloon in the air by blowing through straws)
Magic Balloon (two painted bottles, one white and one black, left in the sunlight - the air in the black bottle is heated and causes the balloon to expand.)
Balloon water pump
This one caused the most surprise - they decided that squeezing the bottle would cause the pump to work and it did but wasn't very exciting. However when we attached the balloon the water overshot our bowl!
They were so impressed with this experiment that they decided to design a larger pump with numerous spouts as a toy for water fights.