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Simple Machines: Catapults

Grades: 5-8
Author: Tracy Wilson, Jason Pitak, Tim Petrie, Jacqueline Godsey, AGPA staff
Source: Original


Working in groups, students will be given materials to build and test a catapult. Then, the groups will exchange catapults so the students can improve on another group's design for accuracy and distance.


What should students know as a result of this lesson?

  • Students will understand how a catapult works
  • Students will understand the engineering design process
  • Students will understand that the solution to one problem may create other problems and require refining the original design
  • Students will understand that the best design may not be feasible because of constraints, such as material availability, cost, or time

What should the students be able to do as a result of this lesson?

  • Students will be able to build a simple catapult
  • Students will be able to evaluate and improve an existing design
  • Students will be able to give and receive constructive criticism


  • 3 rubber bands
  • 2 push pins
  • Wood block; possibly 3"x 3"x 1"; this block will provide the base of the catapult
  • 1 tongue depressor
  • 1 dosage cup
  • 1 ft strip of masking tape
  • Acrylic 1/2" or 1" pompoms, to be launched by catapult



  1. Introduce simple machines to the class by showing a video like the Bill Nye video "Simple Machines part 1", which can be found on Youtube.
  2. Have a discussion of catapults.

Assessment: The assessment is informal. Monitor that the students are watching the video and involved in the discussion following the video. At this time, notice any misconceptions the students may have about catapults.


  1. Students will work in groups and use materials provided to build a catapult. Tell the students that they should use all materials provided for the catapult, if possible. Provide the rubric for grading the catapults to the students.
  2. Groups each launch pompoms and create a data table with 3 trials. Data should include the distance and accuracy of the launch.

Assessment: Monitor that the students are using the materials as intended and that the students are recording the data properly.


  1. Each group presents their catapult to the class describing the strengths and weaknesses of the catapult.
  2. Explain the engineering design process. Have the students discuss their design process. For the engineering design process see Content Knowledge.

Assessment: Use the rubric provided to evaluate the catapults.


  1. Have the groups exchange catapults.
  2. Groups will modify the design of the catapult that they receive and test the new design. The groups should create a data table with 3 trials. Data should include the distance and accuracy of the launch.

Assessment: Each student should do a short write-up that includes: The results from the modifications to the catapult. The student should also make suggestions to improve the catapult with additional materials beyond what was provided in this lesson. The students should include an explanation of the expected results with the additional materials based on the experimentation from this lesson.


An understanding of simple machines is necessary.

Best Teaching Practices

  • Hands-on Learning
  • Inquiry Approaches
  • Real-life Situations and Problem Solving

Alignment with Standards

NGSS Standards:

  • MS-PS2-2 Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.
  • MS-PS3-1 Construct and interpret graphical displays of data to describe the relationships of kinetic energy to the mass of an object and to the speed of an object.
  • MS-PS3-5 Construct, use and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object.

Common Core Standards:

  • RST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts.
  • RST.6-8.3 Follow preciesly a multistep procedure when carrying our experiments, taking measurements, or performing technical tasks.
  • WHST.6-8.2 Write informative/explanatory texts, including the narration of historical events, scientific procedures/experiments, or technical processes.

National Standards:

  • Science and Technology 5-8
  • Physical Science 5-8

Ohio Standards:

  • Grades 6-8: Physical Science Benchmark D
  • Grades 6-8: Science and Technology Benchmark B

Content Knowledge

Information on simple machines can be found at:

Information on the engineering design process can be found at:

Numerous websites can be found on catapults.

Information on kinetic and potential energy can be found at:


Safety goggles are necessary.

General science classroom safety should be followed.


Problem solving skills, working in groups, and accepting constructive criticism are necessary in life. In addition, product development and engineering process design are necessary for students that will pursue careers that need these skills.


Assessments are included at each stage of the learning cycle.

Other Considerations

Grouping Suggestions: At the beginning of the lesson, tell students that they will be trading their catapult with another group and the new group will modify the original design to improve the catapult. Also, explain constructive criticism so the students will understand how to give and receive constructive criticism. Groups should contain a maximum of 4 students.

Pacing/Suggested Time: This lesson should take four 45 minute class periods. This will vary based on the number of groups and the length of the discussions on simple machines, engineering design process, potential energy, and kinetic energy.

Printable PDF Worksheets

Simple Machines Data Sheet

Simple Machines Rubric