Building a Catapult

By Kate Fraser on Feb 04, 2014

Purpose:

To enable students who are blind or visually impaired to design and build a catapult that will toss a marshmallow or pompom over a distance of at least 12 inches, using the appropriate materials and tools safely

Background Information:

Generally in an introductory technology/engineering class, students may be asked to design a catapult that will send a marshmallow flying over a distance. This gives a student a desired outcome, and the student must design a piece of equipment that gets the job done.  Catapults can be simple or complex in design.

Preparation:

To build a catapult, students first need to be familiar with a variety of materials and their properties as well as understand some physics principles. An effective design will reflect understanding of both.  The design shown here requires few materials and tools.  There are many designs available on the web, but a true technology engineering experience involves students creating their own design.  In technology engineering beginning students frequently make diagrams of their designs. Since drawing is sometimes difficult for a student with a visual impairment, adaptive materials such as Wikkistix™ can be used to create a drawing of the design.

Creation of designs can be done tactually, and differences in design can be examined both tactually and visually. Students in their construction will also develop understanding of creating a prototype, testing it out, and redesigning.  The design illustrated was created by one of our students for a science fair. The design propelled the pompom upwards to a height of almost 2 feet but did not propel the pompom forward towards the target. The design and materials for each student would vary. It is important to stress only large soft marshmallows or other soft objects are propelled, and that safety goggles be worn at all times.

Students may be interested in learning about the long history of catapults during battles.

Materials

  • Safety goggles
  • Tray
  • Cloth Tape
  • Masking tape
  • Glue
  • Plastic spoons
  • Marshmallows
  • Pieces of wood in a variety of sizes
  • Craft sticks
  • String
  • Elastic bands

Procedure

  1. Discuss the desired outcome of the project: to design a device that will send a marshmallow or soft pompom flying over the longest distance. 
  2. Collect and examine materials
  3. Create a prototype of the catapult design.
  4. Try out the prototype. 
  5. Did it propel the marshmallow or pompom over a long distance?  Did the missile hit the target? Could the catapult launch a projectile over a castle wall?
  6. Redesign the model as needed.
  7. Compare the design to the design of other catapults

Resources

Club Zoom: Engineering Activity Guide. 2002, pages 7 – 23.
Introduction to Technology, 3rd Edition. 2005, Chapter 7, pages 175 -    187.
McDougal Little Science: Motion and Forces. 2005, pages 108-109.

 

This activity was created by Kate Fraser and Michele Engelbrecht.

collage with catapult model