It's not a solid, It's not a liquid -or maybe it is both - whatever, it is intriguing! (Likely the reason I have vivid memories of my own mom making this recipe with me!)
If you hit it, it becomes solid and breaks. If it sits still, you have a wonderful, drippy ooze. The perfect thing to keep a couple of kids busy!
There are only two ingredients - and both are edible, so you can even invite your teething toddlers to the fun. You'll need a large bag of dry cornstarch, (food coloring optional), and water.
To make: start with TWO part corn starch in a bowl (adding coloring at this point), then, slowly, add ONE part water, mixing with your hands until all the powder is wet.
Now, drop in a little water at a time, mixing as you go. It will not take much water to change the consistency - and you'll know when you have it, because it will start behaving very oddly, breaking all the rules you ever learned in science class. Good stuff!