Closed region

Imagine you have a piece of paper with a picture on it. You draw a line around the picture to show where it ends. This line makes a shape, kind of like a fence around the picture.

A closed region is just like that fence around your picture. It's a shape made by drawing a line all the way around, with no gaps or holes. It's closed because nothing can get in or out through the edges.

Think about a pool in your backyard. If it had a fence all the way around it, that would be a closed region. No one could walk through the fence to get in or out of the pool area.

Math also uses closed regions to describe shapes that have boundaries or borders. A circle is a closed region, because it has a line all the way around it with no gaps. But a donut shape is not a closed region, because it has a hole in the middle where things could pass through.

Closed regions help us understand boundaries and limits, whether we're talking about pictures, pools, or math problems.