Overview:
In this project, students design and construct a catapult type device to launch a large marshmallow at two different targets. The catapult must be powered by a single mousetrap. The device needs to be adjustable so the launch angle can be altered to hit targets at different distances.

Specifics:

• Explain the following requirements to the class:
  
  • The catapult needs to be designed to launch large marshmallows.
    
  • Only a single mousetrap may be used to launch the marshmallow.
    
  • The spring of the mousetrap may not be altered in any way (This is a safety precaution. Winding the spring tighter can result in the spring breaking.)
    
  • The device must sit on the floor by itself during launching. (It may not be held down by the student.)
    
    

• Explain the testing procedure. Two targets will be set on the floor at the distances of 5 meters and 7 meters respectively. Each person will be given 3 shots to launch a large marshmallow (provided by the teacher) in an attempt to hit as close as possible to each target. The device will be placed on a starting line with the spring of the mousetrap centered above the starting line. The grading scale will be determined by the distance from the center of the target.
  

• The score will be the best of the three shots.
  
  

The objective of this project is to expose students to concepts of simple machines, forces, and projectile motion.

Timeline:

The majority of the work should be completed out of class (6-8 weeks). One class period should be used to introduce the activity. One to two class periods will be needed to test the devices. A practice/workshop day is highly recommended halfway through the project.

Materials:

Construction Materials-The students should supply materials to fit their own designs. Some materials they may wish to have are the following:

• one mousetrap
  
• plastic spoons (lever arm extensions and marshmallow holders)
  
• material for a base such as wood, bricks, books, etc... (the base needs to be fairly massive to prevent movement)
  
• hinges to allow adjustment of the trajectory
  
• doorstops or wedges are often used to adjust the launch angle
  

• Target (This can be as elaborate or as simple as you like. A simple piece of tape at the target distances works well.)
  
• Corn starch (This is optional. If you dip the marshmallow in cornstarch before launching it will leave a mark on the floor at the point of impact.)
  
• Meter stick for measuring the distance from the center of the target
  
  

1. Quality and originality of design-A small portion of the student's grade should be based on the overall quality of the finished mousetrap catapult. This will reward students who invest more time in planning, drawing, and building the project.
   
   
2. Performance Score-Two targets will be set on the floor at the distances of 5 meters and 7 meters respectively. Each person will be given 3 shots to launch a large marshmallow (provided by the teacher) to try to get as close as possible to each target. The grading scale will be determined by the distance from the center of the target. Only the best shot will be used to determine the grade. The following is an example of a possible scale:
   Grading Scale:
   A range-- The marshmallow lands within 25 cm of the center of the target.
   B range--The marshmallow lands within 75 cm of the center of the target.
   C range--The marshmallow lands with in 150 cm of the center of the target.
   D range--The marshmallow lands at a distance greater than 150 cm.
   (Consider awarding bonus points for a bullseye)
   Each target is 50% of the total performance grade.
   
3. The paper-Each student's paper should be graded based on the the explanation of the catapult and how the catapult works. Specific questions about the science behind the catapult should be included in the paper. (Sample paper template.)
   
   

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