Think of evolution like a giant puzzle. Each piece of the puzzle is a tiny change in living things, like animals or plants, that happens over a long time. These changes help them fit better into their homes, like how you get better at solving puzzles the more you practice. Some changes are good, and they help the animals or plants live longer and have more babies. Those good changes stick around, like keeping the best puzzle pieces to make the picture clearer.
Another way to think about evolution is like a big family tree. Imagine all the animals and plants in the world are part of one big family. Long, long ago, there was a great-great-great-grandparent that started the family. Over time, the family grew, and each new branch on the tree is a different kind of animal or plant. Some branches are close together because they are more alike, like brothers and sisters, while others are far apart, like distant cousins.
Imagine evolution as a race where the track changes all the time. Animals and plants are like runners in this race. Some runners are fast on certain tracks, while others are better on different tracks. When the track changes, the runners who are best at running on the new track win the race. They get to keep running and have little runners of their own. This is how the race keeps going, changing, and evolving.