Living things notice what is happening around them and react to it. A plant turns toward sunlight. A rabbit runs when it hears a loud noise. You put on a coat when it gets cold. This ability to respond to the world is one of the signs of life.
Place a plant near a window and observe how its leaves turn toward the light over several days. Play a game where children respond to different signals (clap = jump, whistle = freeze). Discuss how animals react to sounds, weather, and danger.
Imagine you are outside and it starts to rain. What do you do? You probably run inside or open an umbrella. You noticed a change (rain started falling) and you did something about it (found shelter). That is called responding to your surroundings, and every living thing does it.
Animals respond to things all the time. A squirrel sees a hawk and freezes or runs up a tree. A dog hears its name and comes running. A turtle feels danger and pulls into its shell. These responses happen because animals can sense what is going on around them — they see, hear, smell, feel, and taste the world — and they react to stay safe, find food, or take care of their babies.
Plants respond too, but much more slowly. A houseplant near a window will slowly bend its stem and leaves toward the light. If you move the plant to the other side of the room, it will slowly turn again. Roots grow downward into the soil, toward water. Some plants, like the Venus flytrap, can even snap their leaves shut when a bug touches them. Plants do not have eyes or ears, but they still sense and respond to things like light, water, and touch.
Nonliving things do not truly respond. A rock sits in the rain and does nothing. A chair stays put when the lights turn on. Even a machine like a thermostat that "reacts" to temperature is not really responding the way living things do — it was programmed by a person. Living things respond on their own because it helps them survive.