What is at the same time a liquid and a solid??? A Non-Newtonian fliud that was featured in Dr. Seuss' book, Bartholowmew and the Oobleck. Push your hands into the mixture of corn starch and water to mix it around and its a fluid that drips off your fingers. However, step on it or hop on it and it acts like a solid. You can see the joy on our students' faces as they check it out. Our older students enjoyed testing it, too. The students even got Miss Vickie to try it and she was so surprised that she could walk on the surface.