Cornstarch goo is a fun activity for children of all ages, but it is also a neat science trick. The mixture of cornstarch and water creates a suspension, where the cornstarch does not actually dissolve but spreads out throughout the water. It can be called a Non-Newtonian liquid, as it does not follow Newton's laws of liquids because it is changed by stress instead of heat. Cornstarch goo pours like a liquid but acts like a solid, which is what makes it such an engaging texture to explore for children.
Make Cornstarch Goo
Measure 5 teaspoons of water into a bowl. Add 2 to 4 drops of food coloring if you would like. Stir gently to mix the color into the water, adding more as needed to reach the desired hue.
Measure a level 1/4 cup of cornstarch and add it to the water. Swirl the bowl so the ingredients start to combine and then let it sit. After about 1 minute, stir with the spoon to be sure there are no lumps.
Test the consistency of the cornstarch goo. It should feel solid to the touch but pour out of the container like a liquid. Add more cornstarch or water to thicken or thin the mixture as needed.
Play with the Goo
Explore the texture by poking it with a finger, trying to stir it with a spoon, or letting it drip off a spoon or your hands. Try squeezing it, rolling it, bouncing it, or spreading it around as well.
Watch the goo act like quicksand by putting a small plastic toy in the goo and then try to get it out. Bury your hand in goo and then try to pull it out to see the same effect.
To clean up the goo, place or guide it into a disposable bag and discard. Wash with water.
To save the goo for later, place in an airtight bag or container. Add a few drops of water when ready to use to achieve the correct consistency. The goo may also be left out to dry and then smashed into a powder to store. Add water to reconstitute.
Do not dispose of cornstarch goo down a sink, tub or toilet as it can clog them. It should be put into a trash can.
Food coloring may stain hands. Rubber gloves can be worn if this is a concern.