--- title: "Marshmallow Challenge" description: "Small teams have 18 minutes to build the tallest freestanding structure using 20 spaghetti sticks, tape, string, and one marshmallow on top. Teams measure results and reflect on unspoken assumptions and early prototyping." last_updated: "2026-09-07" canonical: "https://unitedwetransform.com/exercises/marshmallow-challenge/" --- # Marshmallow Challenge Small teams have 18 minutes to build the tallest freestanding structure using 20 spaghetti sticks, tape, string, and one marshmallow on top. Teams measure results and reflect on unspoken assumptions and early prototyping. **Time:** 40 minutes. Source records specify an exact 18-minute building countdown within a 30 to 60 minute session; UWT allocates 40 minutes to include briefing, measurement, and debrief. **People:** 3 to 24. Small teams of 3 to 6 participants working around separate flat tables. A single team of 3 works if attendance is minimal. ## Choose this exercise **Purpose:** Test team assumptions about planning and rapid prototyping by assembling a freestanding physical structure under a strict time limit. **Use it when:** Use during project kickoffs, design sprints, or team workshops when participants need to observe how they handle assumptions, physical testing, and real-time collaboration. **Skip it when:** Skip when flat work surfaces are unavailable, when participants cannot handle brittle materials, or when the group needs an abstract strategic discussion without physical assembly. ## Materials and tools - 20 sticks of uncooked spaghetti per team - 1 yard (or 1 meter) of masking tape per team - 1 yard (or 1 meter) of string per team - 1 standard regular marshmallow per team - 1 paper lunch bag or large envelope per team kit - 1 pair of household scissors per team - 1 measuring tape for facilitator scoring - 1 digital countdown timer visible to the room ## Before participants arrive 1. Assemble team kits in advance by placing 20 spaghetti sticks, 1 marshmallow, 1 meter of tape, and 1 meter of string inside an opaque paper bag or envelope. 2. Place one unopened kit bag and one pair of scissors next to it on each flat team table. 3. Configure a visible digital countdown display. ## Say this to open Welcome. Each table has an unopened kit and scissors. Please leave the bag closed. Your team has exactly 18 minutes to build the tallest freestanding structure possible. The entire marshmallow must sit on top. When time runs out, nobody may touch the structure. We will measure from the tabletop to the highest point of the marshmallow. ## How to run it ### 1. Brief rules and review constraints (5 minutes) Point to the closed kits. State the five rules: 1. Build the tallest freestanding structure resting only on the table. 2. The entire marshmallow must sit on top; cutting or eating it disqualifies the team. 3. Use as much or as little of the 20 spaghetti sticks, string, and tape as needed; do not use the bag. 4. You may break spaghetti and cut tape or string. 5. Hands off when time expires. Answer quick questions and start the clock. ### 2. Build structure against the clock (18 minutes) Teams open kits and begin construction. Announce remaining time at 12 minutes, 9 minutes (halfway), 5 minutes, 3 minutes, 1 minute, 30 seconds, and the final 10 seconds. Encourage teams to observe neighboring designs. Reiterate that anyone touching or supporting a structure when time ends faces disqualification. When the timer sounds, verify that all hands are raised away from tables. ### 3. Measure structures and record heights (5 minutes) Walk to each table with the measuring tape. Measure from the tabletop surface to the top of the marshmallow for every standing structure. Disqualify any structure that requires hand support or collapses while measuring. Announce the heights from shortest to tallest and confirm the highest standing structure. ### 4. Reflect in small teams (6 minutes) Ask teams to sit together and examine their experience. Have each group select a spokesperson. Teams discuss two prompts from the board: At what minute did your team first test the marshmallow on the structure? What initial assumptions about the materials or plan proved incorrect? Spokespersons prepare one concise observation to share with the whole room. ### 5. Debrief prototyping insights (6 minutes) Bring the room together. Invite 2 or 3 team spokespersons to share their observations. Connect their feedback to the core lesson documented by Tom Wujec: teams that spend all their time planning without testing the marshmallow often discover its surprising weight too late. Teams that build and test prototypes early uncover material limits while time remains to adjust. ## Debrief questions - At what minute did your team first place the marshmallow on the structure? - What initial assumptions about the strength of the spaghetti or the weight of the marshmallow proved wrong? - How did time pressure affect your decision making and willingness to change designs? **Finished output:** Height measurements for each team structure and shared group insights on early prototyping versus late testing. ## Remote Remote delivery requires mailing or distributing identical physical kits to participants in advance. Each participant works solo at their desk on camera for 18 minutes. The facilitator runs the timer, and participants measure their own standing structure on screen with a tape measure. A software-only drawing alternative changes the core physical mechanic and is not equivalent. ## Hybrid Form distinct in-person teams and remote individual builders. Do not mix remote and in-person members in a single construction group. Remote members build their own structure at their desk on camera using an identical kit while sharing audio with other remote builders. Facilitators measure in-person towers while remote participants display their measurement on camera. ## Access and participation choices - Participants with limited manual dexterity may act as team strategists, timekeepers, or spokespersons without assembling brittle spaghetti. - Any participant may choose to observe the team dynamics and contribute during the debrief instead of handling the materials. ## If the session gets stuck **A team holds their structure upright as the final seconds count down because it cannot stand alone.** Firmly enforce the hands-off rule at zero. Remind the group that an unstable structure provides a great learning opportunity for the debrief. **A team attempts to tape their tower directly to the table or a nearby wall for support.** Clarify that taping the structure to the table surface, walls, or fixtures violates the freestanding requirement. ## Terms used here - Freestanding: Supporting its own weight on a flat surface without being held, taped to the base, or anchored to walls or ceilings. - Rapid Prototyping: Building quick physical drafts early in a process to test assumptions before committing to a final construction. ## Sources and adaptation Observed in the Relationship Makers Handbook and the Hyper Island toolbox on SessionLab. Attributed to Tom Wujec, with community commentary citing Peter Skillman. Retained the core materials, 18-minute construction limit, and measurement criteria documented by Tom Wujec and preserved in Hyper Island and Relationship Makers Handbook records. UWT structured the facilitation flow into a 40-minute format, condensed step instructions to stay well below length thresholds, set group minimum to 3 to accommodate small teams, aligned debrief prompts across steps, and specified fair hybrid and accessibility arrangements. [SessionLab](https://www.sessionlab.com/methods/marshmallow-challenge) Current run sheet: https://unitedwetransform.com/exercises/marshmallow-challenge/