Matter is changed physically or chemically. A physical change occurs when matter changes its appearance but not its identity. A physical change includes a change in the state of matter, size, or shape. When making Oobleck, a physical change occurs by adding water and food coloring to cornstarch. The substance is still cornstarch only the state of the cornstarch changed. However, Oobleck is a substance that acts like a liquid and a solid so it is a non-Newtonian substance.

A chemical change occurs when the chemical composition of one or more substances changes into a new substance. A chemical change can be identified by the formation of precipitation, formation of gases and bubbles, temperature changes, odor change, or color change.  Elephant toothpaste is a chemical change because a new substance is formed when the yeast acts as a catalyst. The yeast reaction causes the oxygen in the hydrogen peroxide to break apart. This reaction produces lots of bubbles and a change in the temperature of the foamy substance we call Elephant toothpaste.