Corn Starch Goo

If you have never tried this before, this is what you should do on the next rainy day. It is really easy and fascinates children of all ages (and their parents, too!).

All you need is corn starch (you should get that in any supermarket) and water. Take a bowl and put a cup of water in. If you want you can add some food color. Then add the corn starch (about 2 cups) in small portions and continuously stir slowly.

You will notice when the mixture is right, cause stirring it will become difficult. That is, because the goo (also known as "Oobleck") is a so-called non-Newtonian fluid. When a force is applied to it, its viscosity changes and it starts acting more as a solid than a fluid. Without the application of force it looks like a normal liquid again.

Now the fun starts. Try the following:

• stab it with your finger
• turn the bowl upside-down quickly (if the mixture is right this will not end up in a mess, at least if you hold the bowl only for a short time in this position...)
• put a spoon into the goo, try to pull it out quickly
• put some goo on the spoon and let the goo flow off the spoon

I'm sure you'll come up with more experiments.

And in case you can persuade someone to fill his/her pool with corn starch goo, try this: