Food Web
A food web is a map of which living things eat which in a place where they all live together.
Think of it this way
Six bowls sit on a counter in three rows of two. The small ones are in front, the large ones in back. Yarn connects them to show who feeds whom. Some bowls link to more than one, so the yarn crosses like a web.
Explaining food web by grade level
In a patch of dirt, bugs eat dead leaves. Birds eat the bugs. Cats may eat the birds. Every living thing is linked by what it eats. If one part goes away, the rest feel the change.