All the boys, the little one included, had no trouble blowing up a balloon.
Until we put it in an “empty” soda bottle that is.
Cameron couldn’t even get it to blow up.
That empty bottle wasn’t really empty after all. The air inside was taking up space preventing the balloon from filling up with air from outside.
Little mind officially blown!
Smaller on the Outside 
Cool experiment… I had never seen that before! Gonna have to try it – thanks 🙂