Oobleck is a non-Newtonian fluid made from a mixture of cornstarch and water. When pressure is applied, it behaves like a solid, but when left undisturbed, it flows like a liquid. This unique property makes it a fun and educational substance to experiment with. The name "Oobleck" comes from the children's book Bartholomew and the Oobleck by Dr. Seuss. In the story, Oobleck is a green, gooey substance that causes chaos in a kingdom. The playful nature of Oobleck has made it popular for science demonstrations and hands-on learning activities.