MnSTEP Teaching Activity Collection > MnSTEP Activities > Catapults: controlled investigations

Catapults: controlled investigations

Ted Fraedrich
Ramsey IFAC
Minneapolis, MN
Based on the original activity, "Flippers", from the FOSS kit, Variables. See
Author Profile


In this structured inquiry, students will investigate a catapult system. Having previously explored and identified the variables of the catapult system (length of lever, mass of shot, angle of catapult), students will conduct controlled experiments and display data on a two-coordinate graph.

Learning Goals

Students will understand that a controlled experiment compares a standard to a single variable and that multiple trials are conducted. Students will communicate the data results on a two-coordinate graph. Vocabulary: control, standard, trial, independent and dependent variable.

Context for Use

This investigation is appropriate for an intermediate classroom. Students will already have built and explored their catapult systems. They will already understand that the variables are lever length, mass of shot, and angle of catapult.

Subject: Physics:Classical Mechanics:Projectile Motion
Resource Type: Activities:Lab Activity, Classroom Activity
Grade Level: Intermediate (3-5)

Description and Teaching Materials

1. Review controlled experiments. Make sure students understand control, variable, standard, multiple trials.
2. Describe the standard launch: Launch angle at 0 deg. (flat), shot object is a large foil ball (foil is 20 cm X 20 cm before it is wadded up), lever is all the way in, lever depressed all the way in.
3. Describe the possible experiments. Length of lever, it should be pulled out in 1 cm. increments. Angle of launch, in 10 deg. increments. Mass of shot, made from 10X10 cm sheet, 20X20 etc. Distance lever is depressed; pennies may be placed underneath lever as spacers.
4. Assign or allow groups to choose which experiment they will conduct. Remind groups that they should change only the one variable and that they should conduct multiple trials, four is suggested.
5. Students should keep chart of data in notebook. Results of trials should be averaged.
6. After experiment is completed present two-coordinate graph. Label axes with dependent and independent variable. Each student should create their own graph.
7. Each group should present their results to the class.

Teaching Notes and Tips

Please see for a description of the catapult system. It may be best to break the activity into two parts, the running of the experiment and describing/displaying data.


Assessment is informal observation and review of student's graph.


5.I.B - Scientific Inquiry - The student will understand the process of scientific investigations.

References and Resources