Crater Maker

Where do craters come from?

When we look up at the Moon, we see that it is pock marked with countless craters. We have craters here on Earth, too (though many fewer). It is these craters, along with some of the geological activity of the Moon from a long time ago, that makes those distinct patterns on the Moon’s surface that different cultures equate to a “man in the Moon”, or a “rabbit in the Moon.” Studying the process by which these craters came to be is not only good learning…it is a lot of fun too. In playing around with making their own little craters, children practice experimenting, measuring, isolating variables, and more.

Preparation

This activity is great to do outside, since sand may spray out of the containers during the experiments. If you do it inside, you should choose an area you can sweep easily, and possibly lay down tarp or poly sheeting, aka painter’s plastic to catch the sand.

If you are using the pool, pour your sand into it. You’ll need a few bags, but you can leave it out after this activity as a sand box for younger kids to play in. If you are using buckets, pie plates, or aluminum baking pans fill these with sand to a depth of at least 3 inches, or 8 centimeters.

Collect rocks from around the neighborhood. Ideally you will have rocks of different sizes and shapes. All rocks should be easily handled by kids. Group the rocks as “small”, “medium” and “large”, using their relative sizes.

Resources

Mars Crater

Daedelus Crater on the Moon

Crater on Dwarf Planet Ceres

Craters on Saturn's Moon, Enceladus

Manicouagan Crater in Quebec, Canada

Suggested Materials

Small plastic pool, large buckets, pie plates, etc. (just nothing made out of glass)
A few bags of sand
Rocks
NASA images of craters (see Resources, below), printed out or on a screen
Measuring tapes
Paper and pens or pencils

Opening Discussion

Ask your students if they have ever heard of craters before. Where might they see craters? Encourage responses like “the Moon”, “planets”, and also “on Earth”. What do they think causes craters? Lead the discussion toward the response that craters are often caused by objects (like meteorites) smashing in to the ground. Show the group some of the NASA images of craters you printed out or can share on a computer, from Resources, above. What do they notice about the shape of the craters? Ask them if they think every crater looks the same, or if craters come in different shapes, sizes, and depths. What might cause these differences? Ask them to list the different factors (or variables) that might cause different-sized or shaped craters. Write this list down on a piece of chart paper or dry erase board. Make sure the list includes:

The size of the object smashing in to the ground
The speed of the object smashing in to the ground
The weight, or mass of the object (while the two are not the same, it is OK for this experiment for kids to use them interchangeably)
The material the object smashes into

Then, ask them if they would like to experiment by creating their own small craters, and seeing how craters are formed.

The Challenge

Make your own craters, and learn a little about how they form!

Doing the Activity

Have children work in teams of 2-4 for this activity. Hand out a bucket, pie plate, or pan filled with sand to each team, or have them gather around the plastic pool if you are using it. Give each team a measuring tape and paper and pen.
Ask each team to take turns with the roles involved in this activity. Those roles are:
- Crater Maker – this person drops the rock into the sand-filled container. Important note – they are dropping, not throwing their rocks.
- Measurer – this person measures the crater that the Crater Maker created.
- Recorder – this person is responsible for recording the measurements and observations of the team.
After teams have chosen roles (and remind them that every child will get a chance to be the Crater Maker, etc.), have the Crater Maker choose a rock from your collection. Do they want a small, medium or large rock to start with? They should use this same rock for their first round of experiments. The recorder should call this “Meteor 1”, and should write down if it is a small, medium or large rock.
The Crater Maker should stand over their sand-filled container and hold their arm out at the height they are going to drop it. The Measurer should measure from the ground to how high the rock is, and ask the Recorder to write down that height under the heading “Meteor 1, Trial 1”. The Crater Maker can then drop the rock, and the Measurer should measure how wide across the crater is that the rock created in the sand, and ask the Recorder to write down that crater measurement.
Teams should smooth out the sand and try their test out again, using the same rock, same Crater Maker and same dropping height, and record the results.

Let’s Talk About It

After their first round of tests, bring the teams together to share their results. Have them show the rocks they used. If you can, create a chart for each team, listing rock size, drop height, and crater width for each trial. Ask your students what observations they made. Do they notice a difference between the small, medium and large rocks? If not, how big a rock do they think they would need before they notice a difference? What other variables from the list you created, can they test? For instance, would a crater look different in wet sand vs. dry sand (testing the material variable)? How about differences between their original drop height and a lower or higher height? Emphasize for students this important rule – they should only change one variable at a time. For example, if they would like to compare different materials – like wet vs. dry sand – then they should use the same rock, dropped from the same height, by the same Crater Maker, once with wet sand, and once with dry sand. If they are testing the speed variable (which changes based on the height they drop the rock from), then they should use the same rock, same Crater Maker, and same material.

Build On What They Talked About

Have teams go back and try again. They should all switch roles so that a new team member can be the Crater Maker, the Measurer and the Recorder. They should also remember to smooth out the surface of their sand before each test. The new Crater Maker from each team should come up and choose a new rock, ideally of a different size (though it can be the same size, as long as it is a new rock). Have them run their tests again, share results again, and keep testing until each team member gets a chance to be the Crater Maker.

Encourage teams to use the same drop height as their previous test when they choose a different rock size. If they choose a rock size that they have tested before, encourage them to change their drop height. What do they notice?

Suggestions

What would happen if you dropped a rock from higher than you can reach? What if you tossed a rock at an angle, instead of dropping straight down? What results would you get if the sand was wet instead of dry?
Trying this activity with younger kids? Just having them drop rocks and observe what happens is still a great activity.
Want to get even fancier? Check out this activity about impact craters on NASA’s website, which introduces even more variables and is a great activity for older kids: https://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/Impact_Craters.html#.VrO2-tIrJhE
For some great NASA images of the moon and craters, look at this gallery: http://solarsystem.nasa.gov/planets/moon/galleries (it has lots of other moon related images too).
Visit https://www.nasa.gov/ to search for lots more images of craters.

Earth and Space science activities were developed with the support of NASA. This material is based upon work supported by NASA under grant award number NNX14AQ83G. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Aeronautics and Space Administration (NASA).