Sometimes the simplest of ingredients can make for an afternoon of fun, and believe it or not, cornstarch and water are a great example of that. You can combine these two things to make a really fun “goo” that acts like a solid and a liquid at the same time. It’s a great learning activity and produces a fascinating, tactile material that will really get your kids thinking about how things work.
A child I used to babysit years ago taught me this trick and I recently passed it on to my niece, who thoroughly enjoyed it. It’s inexpensive and easy, but VERY messy, so do this outside if possible!
All you need is water and regular cornstarch. You can add a drop or two of food coloring to the water if you want to color the goo, but beware — this will most likely stain your hands as you play! (Lesson learned when I added a little blue to the water for my niece because I thought she would like it better than just white.)
Start with about a cup of cornstarch and add the water one tablespoon at a time. Stir carefully and add a bit more water or cornstarch as needed to get the right consistency. You’ll know the right consistency when you see it — you won’t quite be able to stir it, but it will still look liquid.
When you get it just right, you end up with a mixture that acts like a solid when you squeeze it, hit it, or press on it, but when you let it relax, it turns into a drippy goo! It’s hard to believe it, but it works. Scrape some up out of the bowl and squeeze it in your hand and you’ll have a ball. Then relax and watch the ball melt between your fingers and drip back into the bowl.
Try to stir it too fast and you’ll see the spoon won’t even budge. Try to poke it with your finger and it will resist and your finger won’t make a hole. Try tipping the bowl and watch what you thought was solid pour right out into your hand. So cool!
When you’re ready to clean up, more water is all you need. When the water greatly outweighs the cornstarch, it stays very liquid and will wipe up (or hose off!) very easily. If you want to reuse the goo another day, just let it sit in a dish until it dries, then crumble it up into a powder. Add water again later to reactivate it and you’re ready to go.
This is a fun rainy day activity for kids of all ages. Toddlers will love the messy fun and the older kids can learn more by researching the science behind it and figuring out why cornstarch reacts the way it does.