Let's get everyone in on the act. Take them into the kitchen. In a bowl, mix about 1/2 box of cornstarch with enough water so that it feels like clay - not too powdery, not too wet. Now pick up this goop and squeeze it - it's crumbly. Hold it loosely - it oozes through your fingers. Knock on the mixture (inside the bowl) and you will find it feels hard. Put your finger slowly into it and...it is liquid. It's solid one minute, liquid the next. Magic!