This is a fun game that can be played with many teams in a competition. Teams build a structure with a limited array of materials and are challenged to make a number of decisions, measuring their success not by performance but rather by return on investment.


  • Building materials (lots of)
    • Paper clips
    • Small rubber bands
    • Ice-Cream sticks
    • 4x2 Lego bricks
    • Post it notes (standard square)
    • String (cut into 10 cm lengths)
    • Tooth picks
    • Straws
  • Marshmallows (lots of)
  • Small envelopes (one per team)
  • Flipchart or board and pens


  • Create a game pack for each team with FOUR of each building material and an envelope
  • Create a “market place” of materials laying out one of each, with a post it note for their cost
    • Paper clips - 1
    • Small rubber bands - 1
    • Lollipop sticks - 2
    • 4x2 Lego bricks - 2
    • Post it notes (standard square) - 2
    • String (cut into 10 cm lengths) - 3
    • Tooth picks - 1
    • Straws - 3
  • Create on a flipchart or board create a scoreboard of :
    • team
    • marshmallows
    • cost
    • ROI
  • Indicate on the scoreboard that ROI = (Marshmallows * 10) - cost / cost



Divide the group into teams of 3 or 4
Assign each team a table
Give each time a game pack


Only materials in the pack and those purchased may be used (The envelope may not be used)
Marshmallows may not be used as building material
The marshmallow(s) must be suspended at least 10 cm above the table
The structure, when measured, must stand freely for 10 seconds
Teams have 20 mins


Score as many points possible, points are awarded for each marshmallow suspended 10 cm above your tables and are deducted for all materials used.


Set the scene: “In this engineering challenge you team’s goal is to build a platform that can hold marshmallows. It must be 10 cm or more off of the table. You will lose points (with 1, 2 or 3) for each item of material you use, but you gain points for each marshmallow that your structure can support.”
Clarify the rules
Continue: “I have giving you packs with a number of materials, if you need more ask me”
Ensure each team understands and start the timer
Teams can “buy” or “return” items with you. There is no currency in this game, simply a calculation for the materials consumed
When teams ask you to adjudicate their structure, first ask the team to calculate their costs, then measure that it is indeed 10 cm or higher. Lastly ask the team to step away and time for 10 seconds.
Record the cost on the scoreboard and calculate the ROI
TIP: This is a great exercise to get photos.
Warn the teams as the time runs out
TIP: Inform teams how the other teams are doing (to encourage competition)
TIP: Inform how previous teams have done (to persuade teams to use more Marshmallows)
Warn the teams with 2 mins to go that it’s their last chance to get measured
At the end of the time stop all teams.
Review the scores, and celebrate the winners.


  • Team with the most marshmallows: what was your driver?
  • Team with the best ROI: what drove you?
  • How did you approach the task?
    • Did anyone plan?
    • Did anyone prototype?
    • Did anyone calculate their return of investment?
  • Was your team always in complete agreement about the construction or the strategy?