Young children often have difficulty characterizing things as living or nonliving. For example, they tend to describe anything that moves as alive. They also do not yet understand the cycle of life (birth, growth, death), and therefore classify as nonliving anything that has died. In science, living is used to describe anything that is or has ever been alive (dog, flower, seed, road kill, log); nonliving is used to describe anything that is not now nor has ever been alive (rock, mountain, glass, wristwatch). Over time, students will begin to understand that all living things grow, breathe, reproduce, excrete, respond to stimuli, and have similar basic needs like nourishment. Older students may even realize that all living things are made up
