Great thing to have,great for camping,(great for anything) its not hard, I mean I'm only 9 and I'm doing chemistry and alchemy.
2.3 quarters of water
Get a bottle, (coke bottles work best) but I'm using a "Sobe" bottle.
Add 3 quarters of water into your bottle
Add vegetable oil almost to the top.
Add at least 10 drops of food coloring.
Add alka seltzer.
Watch it float. P.S red and blue work best.P.S#2 don't put the cap on until it stops fizzing or it will explode.