Activity at a Glance
Making Impact Craters

Purpose
To learn some basic concepts about craters.

Overview
Children examine images of Moon craters and speculate about what caused them. Next, they model the formation of an impact crater. They do this by dropping balls of different sizes and weights from three heights into a tray with layers of different colored powders. They examine the effects of each impact and the features that each impact creates. Children measure crater sizes and draw ejecta patterns to see what effect size, weight, and velocity have on the resulting craters. Finally, children compare the patterns in their testing with the patterns of craters on the Moon to see if their modeling experience gives them additional insights into crater formation.

Concepts

• Impact craters are caused when an impactor collides with a planet.
• A crater's size and features depend on the mass and velocity of the impactor.
• Impact craters provide insights into the age and geology of a planet's surface.
• Impact craters on Earth older than about 200,000 years are worn by weathering, erosion, and plate tectonics.
• Models help us test different variables and understand complex phenomena.

Appropriate Ages
This activity is intended for ages 10–14.

Time
90 minutes

Materials

• Pictures of craters on the Moon or Mars (or both)
• Safety glasses
• One large tub or box per group such as a dish pan, pizza box, aluminum pan, or copy paper box lid (larger pans allow children to drop more marbles before having to resmooth or resurface)
• Fine white powder, such as sand or flour or white sugar
• Very fine, dry powdered tempera paint, pudding, powdered drink mix, cocoa, or colored sand
• Sieve, sifter, large spoon, or cheese cloth to sprinkle the dark powder
• Two same-sized balls of different weights (e.g., marbles, ball bearings, gum balls, wooden beads, moth balls, clay balls, grapes; try to have one light-, one medium-, and one heavy-weight ball). You don't need a set of balls per group — groups can share.
• Two same-weight balls of different sizes (e.g., ball bearings, rubber balls, super balls, golf balls, water-filled ping pong balls, jaw breakers, large gum balls; try to have one small, one medium, and one large ball). You don't need a set of balls per group — groups can share.
• Containers (e.g., cups or plastic bags) to hold a set of balls
• Data chart
• Small irregularly shaped rocks
• Yardsticks or tape measures
• Small rulers
• 3 × 5 index card to smooth the surface of the powder
• Toothpicks
• Newspaper or drop cloths
• Large sheets of paper to record ideas from the discussions

Last updated
February 23, 2005