Explain that a balloon expands when you blow air into it because blowing air into the balloon creates greater air pressure inside the balloon than outside the balloon.
Matter: Properties and Change
In prior grades students learned to identify different physical properties of matter and to realize that an object may be made from several different types of materials. In grades 4-5 students learn that a given substance may exist in different states-solid, liquid, and gas-and that many substances can be changed from one state to another. This understanding of matter lays the foundation for later explanations of matter in terms of atomic theory.
Air is a gas. Air fills a closed container completely. Wind is moving air.