A simple substance that cannot be broken down into other substances. For example, water is made up of the elements hydrogen and oxygen.

A series of events that happen in a regular order and repeat over and over again. Like the seasons, they go in a circle.

To rot or break down into smaller parts. It's like when a leaf falls from a tree and slowly disappears.

Chemicals that are used to clean things, like soap. They help to get rid of dirt and grime.

Non-living parts of an ecosystem, like air, water, sunlight, and rocks.

The movement of important chemicals, like carbon and nitrogen, through living things and the environment.

Living things in an ecosystem, like plants, animals, and bacteria.

A place where something is stored or collected, like a bathtub for water.