For each sponge bomb, you will need 3 sponges, 1 rubber band, and scissors, and some help from a grown-up.
Take one sponge and peel off the scratchy green backing. Do this for all three sponges.
Take the scissors, and cut each sponge into three strips
Stack the strips in a 3 by 3 pattern
Grab the stack and wrap a rubber band around the middle, several times, so it sits tightly. Separate out the individual pieces of sponge.
To make some more, all you need to do is get more sponges. Now, dip them in water, and throw them at your target for a splashy surprise.