What Does Meteor Size Have to Do with Crater Size?

This activity is designed for students to create an experiment resulting from observations in the world around them. They will relate their observations to events that actually happen. Students will use critical thinking and model development to design an experiment, and then analyze data that they find from their experiments.
Key concepts for this lab include: Craters are caused by meteors much smaller than themselves. Events happening naturally can be duplicated with similar results in a laboratory setting.
Vocabulary for this lesson includes: meteor, crater, impact

This lab will work with 8th-12th grades. Class size would be best at less than 30, but could work up to 45 students, in groups of 3. This lab is a field investigation aimed at having students work outside. Students will enjoy class much more if they are not always stuck inside the classroom. This can be done in the classroom using small boxes filled with sand, but it is much more "life-like" done in an outside setting. Students should have previous knowledge of what meteors are and how they create craters. I usually teach about meteors when I teach about the moon due to the large number of craters there, but it could fit in the planets as well.

This is a lab that helps students understand the reasons meteors cause craters much larger than themselves. When I have done this lab, I usually stay in my classroom using trays of sand and small, plastic marbles. It works fine, but I often hear grumblings about boredom. I will be going to a park near my school from now on. It is not the best situation, but I think it the best option I have. There are spots with a beach, dirt and grass. All of these different forms of "earth" allow for more exploring with meteor impacts. I place students into groups of 3-4, depending on the number of students in the class. Each group will get a meter stick, a piece of string, a bag of objects of different shapes and sizes. I use basketballs, footballs, baseballs, golf balls, and then at least two other odd objects like a stapler or an old book or a big or small rock.

Once the class is at the site, tell students that they will be making observations of their objects and the area around them. We are trying to find some questions that students may have. Give students 7-10 minutes to make some observations using their materials and the area around them. Have them make at least 10 observations and write them in journals or in their notebooks. (The number of observations can vary depending on how often students have done observations. Remind them that it is always good to have a detailed description of what they did to find their answers. Once the time is up, re-convene and discuss what people found. One of the main topics that most students should find is the fact that crater size is always larger than meteor size. This is the main idea that I have had my students learn about. There are many other reasons that craters are the way they are. If students think of one of those and want to experiment, let them. There are no wrong questions that can be answered here.

Once groups find their question that they want to ask, they need to design an experiment. Make sure they know what a good experiment involves. (It might be a good idea to go through the scientific method with the class before introducing this lab, if the class does not have a good grasp on it already.) The experiments should start with the purpose, in this case, "We want to find out if meteor size has to do with crater size?" Remember, these can vary from your students a bit. Materials should be listed, as well as the procedure. (One thing I routinely mention to my students is that their procedure should be clear enough so someone can use their lab write-up and re-do the lab exactly as they did it.) A table should be made showing the results of the experiment. Most experiments are done with numerous trials and an average being found. Definitely do that here too. All good experiments show a chart of data found and graphs work well to visualize and compare data. A conclusion must be at the end of the experiment.

• If you are going to a large area, bring a whistle; it is good for getting the students' attention.
• Tell the administration where you are going and when.
• If you are going off school grounds make sure you have administrations permission.
• Same sex groups work well because there will be no "jobs for the girls and jobs for the boys".
• Try to get a variety of different materials to act as meteors. I like to use the different sports balls because they are easily accessible from P.E. Also, get some other objects (Meteors are never perfectly spherical).
• I have never done this experiment outside with my students creating the experiment. It has worked very well inside the classroom with marbles and small trays of sand.
• One thing that most students do not think about when doing experiments is keeping certain aspects set, like the force the meteor hits at or the distance. If they are looking solely at the size of the crater formed, the other variables must be set.

Assessments can be done both during and after the lab experiments. Walk around to each group making sure they are on task and answering questions. Also, ask questions to each group, making them think together for answers. Their responses can go into a preliminary assessment. As students finish their labs, they turn them in for a formal grade. The grading system I use is by section. Students get a certain amount of points for each section of their lab report. Purpose, Materials, Procedure, Results, and Conclusion go into their labs. I also prefer my students to have a graph with their labs, but they would not have to. (I try to integrate as many subjects as I can into my science classes. We graph a lot and write stories and do presentations. This helps students with other classes as well).

8.III.C.3-characteristics of planets
9-12.I.B.1-design experiments
9-12.III.C.2-characteristics of planets