For this month's This is Science, we went to the Chicago Children's Museum, where Laura Wurzburger and Chelsie Burdine helped me make goo.
As with all good experiments, we ran into a snag. The two parts glue and one part starch did not come together quickly enough. Perhaps it was the way I was doing it - squishing it through my fingers rather than kneading it with my palms - or perhaps it was something in the air making things moister. We ended up having to add a little glue. The opposite can also happen - you may need to add starch if it's too thick.
The bottom line is, don't worry if it's not going exactly as you think it should. Stand back and reassess, and you will be fine.
It would also be great if you could share your experience by commenting below, or videotaping yourself and your child(ren) making the goo. We will post it online.
The goo we make, as Laura points out, is not liquid and it's not solid, but it sort of has the properties of both. The proper name is Non-Newtonian Fluid, and we are surrounded by them in our everyday lives.
Not all non-Newtonian fluids act in the same way, and often act differently depending on whether they're moving. You can test this with your goo by constantly moving it with your hands. Observe how it acts like a solid, not losing its shape. Then just stop moving your hands. Observe how quickly the goo seems to melt and lose its shape.
Unlike water, you can walk on non-Newtonian fluids. But don't stop, or you will sink fast. These guys filled a pool with a mix of cornstarch and water (sometimes called Oobleck - from a Dr. Seuss book) and show clearly how motion keeps them up and stillness makes them sink.
There are lots of non-Newtonian fluids in your house. Some are more runny than others, but they all have uneven flow when poured. A great way to teach your kids to identify non-Newtonian fluids is to have a scavenger hunt. Here are some clues you can use:
This red substance makes everything good to eat.
Pour it on fries or hot dogs, or broccoli for a treat.
Pour this on pancakes, but don't get picky.
If you stick your fingers in it, you will get sticky.
Too much sugar and you'll have to brush out.
This minty stuff will make your mouth happy, no doubt.
Fingers and brushes turn this into art.
Tell mommy you love her, and make a big heart.
For milk that is chocolatey, or eating ice cream,
this topping makes dessert a sweet dream.
This squishes your hair up into all sorts of things.
Make it look like a crown and pretend you're a king.
But be careful of dripping, or your eyes will sting.
Other non-Newtonian household fluids are:
You can also bake some bread with your child. That dough is definitely a non-Newtonian fluid.
Of course, you can buy non-Newtonian fluids like Silly Putty or Play-doh, but it's more fun to make it at home.
And, to distract your child from the pain, the next time he or she gets a cut, explain as you're putting on the bandaid that blood is also a non-Newtonian fluid.
Here's a really great website that explains both Newtonian and non-Newtonian fluids.
(Answers to rhymes: ketchup, syrup, toothpaste, paint, chocolate syrup or sauce, shampoo.)
See more science experiment videos
Optional fun materials:
"One part starch, two parts glue, come together, make some goo."
Keep this chant in mind as you make your concoction. We made about a pound of goo, which required two quarter cups of glue and one quarter cup of liquid starch.