Gravity holds water and air near the surface of the earth and affects how they move around. Find where water is added to the stream table and where it leaves. The stream table shows how gravity makes rivers flow from higher areas to lower ones. Besides a river, give three other examples in nature where gravity pulls water down. Watch several of the balls as they follow different pathways.
Gravity pulls down on airplanes and birds.
That means that flying things all rely on other forces that are stronger than gravity to keep them up. Sometimes air can provide the force to overcome gravity. Take the beach ball off the blower and hold it above the floor as high as you can. Hold the ball above the blower and drop it. Gravity pulls down on a roof, helping to keep it on the house.