Before you begin, instruct the kids that although this is a homemade recipe, it is for fun and play, NOT TO EAT.
Pour the cornstarch into the bowl. Have the kids sift with their fingers. (Although this is an easy craft activity, keep napkins or a towel close by in case of spills.)
Pour the glue into the bowl.
Mix well. Once again, this can be a messy kids craft. My suggestion is to make homemade goop in the kitchen, not the living or dining room. You don't want this on the couch a year from now.
Mix water food coloring and Borax in a separate bowl. Mix until dissolved. Don't worry about the food coloring, let the kids enjoy this easy craft. The idea of food coloring staining fingers sends some mothers into a panic. Don't worry, a little vinegar will take it right off.
Pour the two mixtures together. Stir for 3 minutes, even after you see the homemade goop forming. This is to make sure it's mixed all the way through. Let the kids help with this fun and easy part.