What you'll need:

big potato (unpeeled and raw), stiff straw

How it works

When you place your thumb over the top end of the straw, air gets trapped inside. When you trap the air inside the straw, the air molecules compress (squeeze together) and give the straw strength. The trapped, compressed air makes the straw strong enough to cut through the skin, pass through the potato and out the other side.

Without your thumb covering the hole, the air is pushed out of the straw and it crumples and breaks as it hits the hard potato.

So the secret to this scientific trick is inside the straw: it's air!

 

What you do:

The challenge is to stab the straw through the potato without bending or breaking the straw.

Firstly, hold the potato safely with your fingers on the front and your thumb on the back of the spud. Do not place your fingers on the top and bottom. Now grab the straw with your writing hand and the secret is to cover the top end of the straw with your thumb. Hold on firmly to both the straw and the potato and with a quick, sharp stab, drive the straw into and partway out of the narrowest end of the spud (the fatter middle part might be too tricky).

The best part is seeing if your friends can figure out how to do it too!