“Oobleck,” named for the mysterious green substance described in the Dr. Seuss classic Bartholomew and the Oobleck, is a non-newtonian fluid meaning it doesn’t follow Newton’s laws of motion. A non-newtonian fluid (like oobleck or silly putty) has a different viscosity depending on the force applied. By contrast, newtonian fluids (like water) have a constant viscosity at a given temperature. No matter how fast you stir them they never get thicker or thinner. Oobleck is a mixture of cornstarch and water.