species
A species is a group of living things that share many things in common. They look alike, live in similar ways, and can have babies with each other. The babies they have can also grow up and have babies of their own.
Each species has its own special features. For example, all humans belong to one species because all people can have children together. All dogs belong to another species because all dogs can have puppies together.
Different species cannot have babies together. For example, a cat and a dog are too different. Their bodies, size, and the way their insides work are not the same, so they cannot have babies together.
Every species has its own kind of food, place to live, and way of surviving. Fish live in water and breathe through gills. Birds live on land or in trees and breathe air through lungs. Lions hunt for meat. Cows eat grass. Each species is different in its own way.
There are millions of species on Earth. Some are animals, some are plants, and some are tiny living things we cannot see without a microscope. Even in one small garden, you can find many species of insects, plants, and birds.
So, a species is a big group of living things that are the same kind, can make babies together, and live in their own special way.