Marshmallow Challenge

Choose this exercise

Purpose: Build and measure a freestanding physical structure under fixed resource and time constraints.

Use it when: Use during project kickoffs, design sprints, or team workshops to examine how groups handle rapid prototyping, assumptions, and collaboration under pressure.

Skip it when: Skip when clean table space is unavailable, when food waste concerns make real food props inappropriate, or when participants cannot handle small, fragile materials without frustration.

Group arrangement: Small teams of 4 to 6 people at separate tables. For group sizes that do not divide evenly, form teams of 3 to 7 people, or assign spare participants as timekeepers and observers.

Timing: Playmeo source specifies 20 minutes of building; UWT allocates 30 minutes total to include setup instructions, measurement, and a structured debrief.

Materials and tools

• 20 sticks of uncooked spaghetti per team
• 1 meter (approx. 3 feet) of string per team
• 1 meter (approx. 3 feet) of masking tape per team
• 1 standard marshmallow per team
• 2 to 3 spare marshmallows for facilitator stock
• 1 pair of scissors per team (to cut string and tape)
• 1 measuring tape or meter stick for the facilitator
• 1 countdown timer visible to the room

Before participants arrive

1. Assemble each team's materials kit into a paper bag or envelope.
2. Arrange flat tables so teams have clear surface space without obstructing other teams.
3. Prepare a measuring tape and set up a visible countdown timer.

Say this to open

Your task as a team is to build the tallest freestanding structure you can in 20 minutes, using only the supplies in your kit. The entire marshmallow must sit on the very top of your structure. Freestanding means no one is holding it, and it is not taped to the table, a wall, or any external support when time expires. You may break the spaghetti, cut the string and tape, and use as much or as little of the materials as you wish. Do not open your kits until the timer starts.

How to run it

1. Explain rules and distribute kits 3 minutes

   Hand out one materials kit and one pair of scissors to each team. Ensure participants keep kits closed while you deliver the opening script. Review the detailed constraints: the structure must stand completely unaided on the flat table surface, the marshmallow must stay whole on the highest point, and materials outside the kit cannot be used. Answer any clarifying questions before beginning.

2. Build the structure 20 minutes

   Start the 20-minute countdown timer. Teams open their kits, collaborate, assemble, and test their structures. Announce time remaining at the 10-minute, 5-minute, and 1-minute marks. Remind teams that if their structure collapses or requires someone to hold it when the timer sounds, its measured height will be zero.

3. Measure and record heights 3 minutes

   Call hands off immediately when the timer sounds. Walk table by table with the measuring tape to measure each standing structure vertically from the table surface to the top of the marshmallow. Disqualify any structure that touches hands, walls, or tape anchored to the table. Record each team's verified height on a board.

4. Debrief the building process 4 minutes

   Lead a brief reflection with the whole room. Invite 2 to 3 teams to answer how early they placed the marshmallow on their structure and what happened to their original design plan during the final minutes.

Debrief questions

• At what point in the 20 minutes did your team first place the marshmallow on the structure, and what did that reveal?
• What unexpected structural assumptions failed when weight was applied?
• If your team had to repeat this build immediately, what would you do in the first five minutes?

Finished output: A measured vertical height in centimeters or inches for each team's freestanding structure.

Remote

Physical construction requires tactile materials. For a remote session, mail identical kits to participants in advance or have them source 20 dry spaghetti noodles, 1 meter of tape, 1 meter of string, and 1 marshmallow at home. Run the 20-minute timer over video conference in breakout rooms of 3 to 4, where each member builds an individual structure while discussing design strategy with their peers. At time, each member steps back from the camera and measures their own structure on video.

Hybrid

Form separate in-person teams and separate remote teams. Do not mix remote and in-person members on the same physical build team. Remote participants source their own kit at home and build parallel structures, sharing their screens and measuring alongside in-person teams.

Access and participation choices

• Participants with fine-motor challenges may take active roles in planning, timing, structural observation, or directing assembly rather than snapping and taping materials.
• Any participant may choose to observe, track time, or record measurements without building.
• If handling gelatin or food products is restricted, substitute the marshmallow with an equivalent foam cube of similar weight and size.

If the session gets stuck

A team tapes their structure directly to the tabletop for stability.

Intervene gently during the build or at measurement: clarify that freestanding means the base rests on the table without adhesive anchors.

The marshmallow is cut into pieces or hollowed out to reduce top weight.

Remind the team that the marshmallow must remain intact and whole at the top. If damaged, provide a fresh marshmallow from spare stock.

Terms used here

• Freestanding: A structure that supports its own weight and balance on the table surface without being held, propped against walls, or taped down.