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Lesson: Target Practice – Pumpkin Launcher

catapult studentsLesson from Go FETCH!


In this activity, which can include discussions of simple machines and kinetic energy, teams of students in grades 1 to 6 follow the engineering design process to build and test a rubber band-powered catapult that launches marshmallow “pumpkins.” They then make changes to improve their launcher’s aim and distance it can hurl a projectile.

Grade level: 1 – 6

Time: 45 – 60 minutes (10 minutes prep time, 30 -45 minutes for the activity)


National Science Education Standards

  • Science as Inquiry: Abilities to do and understand about science as inquiry.
  • Physical Science: Position and motion of objects [K-4]; Motions and forces [5-8].
  • Science and Technology: Abilities of technological design, understanding about science and technology

Engineering connection   aircraft carrier

The catapult was used in ancient and medieval warfare to hurl stones and other projectiles at the enemy. Today, catapults are used for other purposes – like launching airplanes from aircraft carriers that have short runways. An aircraft catapult slings a plane forward, helping to create enough lift for a safe takeoff.

Many engineering schools mark Halloween by hosting pumpkin drops and pumpkin-launch competitions. Around the country, local contests have drawn second graders in Colorado as well as high school teams from New Jersey. The Mount Olive Robotics Team, for example, went all the way to the 2011 World Punkin Chuckin’ Championship. Read the Scientific American interview with the teacher and student team leader.

Engineering students vie in the University of Texas, San Antonio, Monster Mash Pumpkin Smash:


For each team:

  • rubber band
  • duct tape
  • craft stickscatapult
  • brass fasteners
  • mini marshmallows
  • scissors
  • pen
  • toilet paper or paper towel tubes
  • plastic spoon
  • cardboard base (chipboard, shoebox, tissue box, cereal box, milk carton, etc.)
  • target (trash bin, for example)
  • meter stick (for extension activity)


Build the launcher:

  1. Attach a toilet paper tube to a cardboard base. This is your fulcrum.
  2. Tape the handle of a plastic spoon to the end of a craft stick. This is your lever.
  3. Use a pen to make a hole in the top of the tube and insert the lever. Secure with tape.
  4. Punch a hole in the base in front of the tube (using the pen), and attach a brass fastener.
  5. Wrap a rubber band around the brass fastener, then around the middle of the lever (so that there is tension as you pull it back). Tape in place.

Launch it! Pull back on the lever and place a marshmallow in the spoon. Then, let go! What happened?

Design Your Own Now that you know how to build one kind of catapult, brainstorm your own design. Try a different base or fulcrum, build a different type of lever, or use the rubber band in a different way.

Test it! Can your marshmallow hit a target? How can you make it go farther? Or higher? Change one thing (a variable), like the length of the rubber band or the position of the lever. Predict what will happen. Then, test it!


  • Hold a Catapult Contest. See whose catapult can send the marshmallow the farthest. Use a meter stick to measure the distance, and then record the results.
  • Older students can write down predictions, results, and conclusions in lab books, and share their redesigns with the class.

Additional resources:

Pumpkin launch device.Mount Olive (NJ) Robotics Team’s floating arm reverse trebuchet that competed in the 2011 World Punkin Chunkin’ Championship contest. Read the Scientific American interview with the teacher and student team leader.

FETCH! Target Practice Activity Sheet in English and Spanish.

FETCH! Challenge Pack. Hands-on engineering and science activities for 6- to 10-year-olds, plus tips for leading them, from

Simple Machines.‘s teacher-tested lesson plan introducing the six simple machines, using examples such as the building of the pyramids and hands-on activities.

Minute Physics. Short videos explaining concepts from simple machines to dark energy.


Watch the University of Rochester engineering school”s annual pumpkin launch:

Lesson adapted from Target Practice! All Rights Reserved, WGBH Educational Foundation, ©2009

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