One of the characteristics of living things is that they can move by themselves, whereas plants rely on the weather or other animals to distribute their seeds. Children learn to walk and move by using their limbs, supported by muscles. Animals fly by flapping their wings, pushing against the air; fish move by pushing against the flow of water. Land animals must balance to remain upright as they move from place to place. Children will notice these phenomena and with a cue word from an adult, they can be assisting to observe the laws of physics, such as force, resistance, heating and cooling. Their play will become more meaningful, especially when it occurs within a relevant context.