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The Mechanically Powered Launcher (MPL) Engineering Challenge

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What is the Engineering Challenge?

Working in teams, grade 5-7 students design, build, and test an engineering prototype. Teachers may recruit a volunteer engineer to work with student teams and guide them in the design and construction of the prototype. Engineers from all disciplines (for example, mechanical engineer, electrical engineer, civil engineer, etc.) have sufficient background to participate in this activity, and are welcome volunteers.

Learning Objectives

Teachers can integrate the Challenge activity into their classroom curricula to help teach the concepts of Forces Acting on Structures and Mechanisms, Conservation of Energy and Resources, and Form and Function.

Students will:

  • plan and design the construction of an engineering prototype,
  • apply understanding of the following curriculum concepts: forces acting on structures and mechanisms, conservation of energy and resources, and form and function. STSE: Impact of various factors in designing and building devices to meet specific needs.
  • communicate their design plans, explaining their design choices and decisions,
  • work collaboratively and effectively in a small group to solve a practical problem.

Teaching Strategies

The Engineering Challenge contributes to a collaborative inquiry classroom culture in the following ways:

  • engages groups of students in a hands-on/minds-on, problem-solving activity,
  • instills the concept of a team approach to solve an open-ended problem,
  • introduces the engineering profession in the classroom.

Activity: Construct an MPL (Mechanically Powered Launcher) Catapult!

The very first reported mineral finds on the surface rocks of Mars were discovered in 2004 by the Mars rovers - Spirit (NASA) and Beagle 2 (ESA). Today, 2050, the first Mars colony has been established.

As one of the scientists on the colony, you have discovered new minerals and urgently need to send them back to Earth for analysis. The colony has only limited building materials and recycled items. You must build a mechanically powered launcher (MPL) to send a capsule containing mineral samples into orbit, where an Orbiter will retrieve the capsule to bring it back to Earth.

The capsule must be launched at a precise angle to escape the gravity of Mars, and reach the proper altitude where the Orbiter awaits.

Design Specifications:

  • The “capsule” (standard ping pong ball) must be launched by the MPL. Make sure you have a device to hold the “capsule” in place.
  • Only the materials listed are allowed. Decorations are permitted and encouraged, as long as they do not interfere with the function of the MPL.
  • The MPL must fit, completely assembled, into a standard photocopy paper box (432mm x 279mm x 225mm), with the lid on. An oversize MPL will be disqualified.
  • All types of launchers are allowed (catapult, trebuchet, slingshot, etc.) but must only be built with the specified materials.
  • No modifications are allowed to the payload (ping pong ball).

Teams consist of 3 to 5 students with the following responsibilities:

  • Designer: With input from the other team members, creates the design and obtains authorization from the teacher or volunteer engineer to proceed with construction. Sketches the team’s design drawing.
  • Materials Manager: Collects and keeps a record of all materials used by the team during construction.
  • Constructor/Builder: Leads construction of the prototype according to the design drawing plan and includes modifications suggested by team mates.
  • Communication Specialist: Spokesperson for the team who presents project to others.

Construction Materials


  • paper, cardboard, newspaper
  • string, yarn, rope, fabric
  • glue, play dough, tape
  • popsicle sticks, tongue depressors, toothpicks, skewers, chopsticks, dowels
  • wooden pencils
  • plastics, styrofoam, rubber
  • CDs
  • spools (wooden, plastic)
  • bottle caps (plastic)
  • paint, decorations
  • straws, rubber bands
  • paper clips
  • sand and Play-Doh


  • glass
  • metal (except paper clips)
  • mousetraps
  • lumber/wood (except popsicle sticks, tongue depressors, toothpicks, skewers, chopsticks, pencils, spools, dowels)
  • construction kits (Lego, Meccano, K’nex, etc.)
  • batteries
  • water

Challenge Construction Tips:

  • Accuracy and repeat performance are key to the success of the mission. Find a way to launch your capsule so that you obtain the same results launch after launch.
  • Consider the different angles required to hit each target and think of ways to calibrate your MPL so that you can successfully achieve various targets. (Hint: think about how you can use a protractor!) Also consider the ceiling height of your launch area.
  • Make sure the MPL is sturdy enough to survive multiple rounds of testing.
  • Try to make MPL as light as possible. The smaller the mass, the higher the score.
  • If there are delicate parts on your MPL, make some “spares” that can be easily fitted in case of damage during the competition.

MPL Testing Criteria:

Once construction is completed, teams gather together to test their MPLs against the other teams in the class and/or school (See “Organizing a Grand Finale” for more details). Test your team’s MPL and see if you have successfully conquered the Engineering Challenge!

  • Teams must attempt to successfully launch their payload and hit targets at 3 different distances – 3m, 4m and 5m. Use standard photocopy paper boxes for targets.
  • Create a launch pad area on the floor, to ensure that all MPLs start the same distance from the target zone. No part of the MPL may cross over the launch line.
  • Mark off a target zone on the floor with masking tape starting with a line at 2.5 m from the front edge of the launch pad. Add more lines at 3.5 m, 4.5m and 5.5m. This creates 3 “target zones” in which to place your target boxes. Target zone width should measure 2 m, with target box placed in the centre. (See illustration below.)
  • Place the first target at 3m, with the centre of the box 3m away from the front edge of the launch pad. Place the second target 4m away and the third target 5m away.
  • Each team will have 2 chances to launch their payload into each target. The payload must land directly in the target (no bounces allowed).
  • Teams will be awarded 1 point for hitting the target zone, 2 points for landing their payload inside the target box and 0 points for landing outside of the target zone.
  • Teams must launch their payload into the 3 successive targets in order, starting with the 3m target.


Judging Criteria:

MPLs will be judged on performance, as well as on the ingenuity of the design and construction. 


Performance will be determined by tallying total points accumulated during payload launch attempts.

Team Name Target 3m Target 4m Target 5m MPL launch points
(max  12 pts)
  Attempt 1 Attempt 2 Attempt 1 Attempt 2 Attempt 1 Attempt 2  
MPL1 1pt 2pts 1pt 2pts  1pt 2pts 9
MPL2 x 2pts 1pt 2pts 1pt  1pt 7
MPL3 2pts  x 1pt  x x 2pts 5


Innovation/ workmanship: ingenuity, imagination, attention to detail 0 - 10
Presentation by Public Relations person and quality of poster   0 - 5
Total Ingenuity Score / 15

Optional criteria: Mass

While this criterion is optional, it is recommended. Scoring should be done on a bell curve with the lightest MPL scoring the maximum score of 25 points.


  Team Name   MPL launch points x 5

  Mass (grams) 

  Ingenuity   Total Score
  /60 /25 /15 /100
MPL1 45 20 14 79

Note: An electronic scoring spreadsheet for the 2011 MPL challenge (.xls format) is available by contacting:

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Guidelines for Teachers and Engineers are available here.

Assessment grids for this activity are available here.