GO IN DEPTH

Your group will watch various objects (pens, pennies, erasers, etc.) fall from the same height to see if they reach the ground at the same time. They also will roll marbles down an inclined plane to see if they reach the bottom at the same time.

Earth’s gravity pulls on all objects. Near the surface of the earth, the acceleration of all objects due to gravity is the same. Drop a penny and a pen from the same height and they will hit the ground at the same time. When objects travel down an inclined plane, gravity is pulling them downward, but the plane is exerting a force on the object, which makes it fall along the plane rather than straight down. Two marbles, regardless of size, will accelerate at the same rate. The two marbles should reach the bottom of the plane at the same time.

**Set-Up**

There are two parts to this activity. The first is just to get kids thinking about gravity. Hold up a penny and a pen and ask your kids: “Do you think these two things when dropped would hit the ground at the same time?” Record student responses on a blackboard or big sheet of paper.

Drop the penny and the pen and ask your kids: “What happened?” Results may vary, but you should tell your group that all things, when dropped near the surface of earth, accelerate at the same rate due to earth’s gravity.

Have kids pair off and make predictions about what will happen when they drop various objects: pencils, erasers, or any items that are safe to drop. They can write their predictions in a science notebook or they can make a data chart with two columns: predictions and results. Then ask students to drop these items. One kid in each pair should do the dropping and the other should observe. Then they can switch.

**Activity**

The second part of this activity is the marble race down the plane. Give each pair of kids a Falling for Gravity activity sheet, a couple of marbles, a ruler, and a binder or books to create an inclined plane and point them toward the student web page. If supplies are short, have groups of four do the activity.

Discuss the results.

Gravity is the force that pulls on every object on earth. Have you ever wondered if the pull is always the same for every single thing? If you drop a penny and a pen from the same height, they'll both hit the ground at the same time. But if you drop a pen and a piece of paper, the paper may drift and take longer to fall than the pen does. Can you guess why? Test gravity with this activity.