Toothpick towers

How tall can you build a tower out of just toothpicks and marshmallows? Try out some of these ideas and see how far you can go!

The Experiment

This experiment is based on a similar experiment by The Exploratorium.

Materials:

toothpicks
mini marshmallows or gum drops
(no glue allowed! :) )

Try it out:

1. To build your tower, attach toothpicks together by sticking them into marshmallows. How? Well that's what you're going to figure out!

Try out different shapes. Do you think your tower can be straight up and down? How about a pyramid? Do you need some diagonal toothpicks to hold your tower up, or can you build straight up?

For an added challenge, try putting a small weight on top of your tower after you build it, like a wooden block or a small book. Does your tower stay standing or does it fall? What shape towers can hold up the weight?

What's happening

When you build your tower, there are a lot of forces acting on the different parts of the tower. Compression force smushes the marshmallows and pulls the toothpicks together. Tension pulls the marshmallows and toothpicks apart. Gravity pulls the tower down.

If there are so many forces, how does the tower stand up? The tower can only stand up when all the forces are balanced. Some shapes can stand up against different forces better than others. For example, if you make a square and there is too much compression force, the square might turn into a diamond:

But if you use a triangle instead, the compression force has to be much bigger to make the triangle collapse. This is because the triangle can balance the compression force with a tension force.

If you thought this was cool...

This experiment is related to civil engineering. You can find out more here.
Some ideas from physics in this experiment include Newton's Laws and forces.