Isaac and his submarine experiment

Don't use up too many empty bottles if you want to do a submarine experiment!

Unless you put a lemon peel submarine into a jar full of water and cut out a balloon circle.

How to set up the experiment:
1) You fill a tub up with water
2) You put the bottle in the tub
3) You breathe in and the water goes higher and higher (or maybe it doesn't at all)
4) You breathe out and it goes down, down, down, down, down... (or maybe it doesn't at all)

issac!