It is as easy as slipping rubber bands over the middle of the watermelon until it bursts.
The rubber bands are much easier to slip over the melon with another person, so this is a perfect social activity. Put on your goggles to protect your eyes before starting, because you never know when it’s going to blow!
Set your melon on a table or other stable surface and one at a time start slipping rubber bands around it. You want to make a big belt of rubber bands around the melon’s middle, so just keep stacking them on top of each other. This is a great activity to keep the kids engaged. Ask them how many rubber bands they think it will take? (And, then don't tell them that it is approximately 325-425 depending on the size and ripeness of the watermelon). The suspense will continue to mount!
Here are some things to discuss throughout the process (a little of the science behind it).
After a few minutes of applying rubber bands, pause and take a look at your melon. Is it still the same shape? You may start to see the top and bottom of the melon bulge out around the rubber bands. Why do you think that’s happening?
You have to stretch the rubber bands out to get them around the melon. But once they’re in place, they start to contract, squeezing the melon. All that pressure from the outside is forcing the inside of the watermelon to find some place else to go, so it’s starting to bulge.
Rubber bands are a great example of potential energy. Potential energy is energy that is stored up, not being used, just waiting to be unleashed. Think about when you stretch a rubber band, then let go and it snaps back. It’s using up its potential energy.
When potential energy is used up, it becomes kinetic energy—energy in motion. So right now all those rubber bands around the watermelon are stretched out and full of potential energy, ready to snap back. But what will happen to the melon in their way?
Keep adding rubber bands and eventually the strength of the rubber bands’ potential energy will put enough force on the watermelon to squeeze the top and bottom of the melon apart. The rubber bands will cut through the melon and contract. What do you expect the melon to do?
Once your melon explodes, the rubber bands will have snapped back and used up their potential energy for now. But you can always stretch them out again!
And, if you are lucky, you may even have a bite of juicy watermelon left!