Step Launcher (Student Instruction)

What do a bat hitting a baseball, a nutcracker opening a walnut, and a trebuchet flinging a boulder have in common? They all make excellent use of levers, simple machines that can convert a small force into a large one, or a small motion into a large one. Engineers use different kinds of levers to accomplish a wide range of tasks.


STEM careers

Grade level


  • A ping pong ball, or small foam ball, to launch
  • Lever materials like
    • paint stirrers
    • rulers
    • spoons
  • Fulcrum materials like
    • thread spools
    • paper towel tubes
  • Tape or rubber bands
  • Feel free to use other building materials you might find at home – be creative!


  1. Identify the Problem
    • The most critical step of any engineering challenge is to understand the problem you are trying to solve.
    • How can you design a way to launch a small ball off the floor so you can catch it? Here are the specs:
      • You may only use one foot to make your launcher work.
      • Your design must launch the ball upward and high enough for you to catch it.
  2. Brainstorm Designs
    • Experiment with your materials and maybe sketch some ideas before you start building.
    • Consider how your materials might affect the ball’s trajectory, or path through the air:
      • Why are ping pong / foam balls challenging to launch straight up in the air?
      • How does the length of the lever affect the trajectory of the ball? What about the placement of the fulcrum?
  3. Build and Test Your Design
    • Choose one design idea and start building!
      • How can you use connective materials like tape or rubber bands to hold your design together?
    • Test your design. Did it work like you thought it would? Are there things you want to adjust or change to make it better?
  4. Make Changes and Try Again
    • Redesign your launcher and test again.
    • If your first design was successful, you can up the ante with a new challenge…like shooting the ball up twice as high or launching it into a wastebasket – the possibilities are endless!
  5. Share Your Results with a teacher, parent/guardian, or DiscoverE
    • Share photos or a video of your launcher in action!
    • Send to DiscoverE at or post on Instagram/Twitter using the hashtag #DiscoverEChallenge


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