All living things grow and change over time. A seed becomes a plant, a puppy becomes a dog, and a baby becomes a grown-up. Growth means getting bigger, and change means looking or acting different as time passes.
Look at baby photos and compare them to how children look now. Track a plant's height each week with a ruler. Talk about how pets were smaller when they were young.
One of the most amazing things about living things is that they grow. You were once a tiny baby, and now look how much bigger you are! Your bones got longer, your muscles got stronger, and you learned to walk and talk. That is growth and change — getting bigger and becoming different over time.
Every living thing does this. A tiny seed buried in the dirt sprouts a stem, grows leaves, and becomes a tall plant. A tadpole swimming in a pond grows legs, loses its tail, and becomes a frog. A puppy with big paws and floppy ears grows into a full-sized dog. Growth is something living things do from the inside — their bodies use food and water to build new parts and get bigger.
This is different from nonliving things that seem to get bigger. A snowball gets bigger when you pack more snow onto it, but that is not real growth. You are adding material from the outside. A balloon gets bigger when you blow air into it, but the balloon is not alive and growing. Living things grow because something inside them is working — their bodies are building and changing all on their own.
Growth does not last forever. Most animals stop growing once they are adults. A dog does not keep getting bigger year after year. But even after an animal stops getting taller, its body keeps changing — hair grows, skin heals, and the body repairs itself. Change is part of being alive, from the very beginning to the very end.