When I breathe, air enters my nose. The inside of my nose warms the air. Little hairs in my nose catch the dust in the air. The wetness in my nose catches most of the germs I breathe in. The warm,...
What is a cell ?
All living things---plants, animals, and people---are made of cells. I am made of cells. A cell is the smallest living part of me it is possible to imagine. A cell can be long, short, thin, fat,...
Building blocks
Atoms are the \"building blocks" of matter. They fit together to make all the things there are. Most kinds of matter are made of atoms that are joined together. These groups of joined atoms are...
Fresh air to breathe
Did you know that every green plant in the world is like a kind of factory? It works from sunrise to sunset making food for itself. As it produces food, it gives off an invisible gas called oxygen....
The air makers
Most scientists think that the first tiny sea plants made it possible for life to come onto the land. To live, plants and animals must take in a gas called oxygen. The tiny sea plants and animals of...
This fish
This is a looking page. What does the picture tell you about the fish? This fish has shiny scales. Scales are like small, thin pieces of fingernail that cover a fish's body. This fish has big,...
Where the air came from
Scientists think the earth's atmosphere has changed during the billions of years since the earth was formed. At first, the atmosphere was probably very different from what it is now. It began to...
Is air something?
live without it. Almost every kind of animal and plant in the world must have oxygen or it will die. Only about one-fifth of the air is made up of oxygen. Most of the air---nearly four-fifths of...