The Marshmallow Challenge: Rules, Instructions and Debrief

The marshmallow challenge is an 18-minute team building exercise. Small teams build the tallest free-standing structure they can from 20 sticks of spaghetti, a metre of tape, a metre of string and one marshmallow, which has to sit on top. It looks like a game. It's really a lesson in planning, prototyping and how your team works under pressure.

What you need

Per team: 20 sticks of uncooked spaghetti, about one metre of masking tape, one metre of string, one marshmallow, and a paper bag to hold the kit. You also need a timer and a tape measure.

Marshmallow challenge rules

• Build the tallest free-standing structure you can.
• The whole marshmallow must be on top.
• Use as much or as little of the kit as you like. Cut the spaghetti, tape and string if you want; the bag can't be used.
• The structure can't be suspended from anything or held up when time ends.
• You have exactly 18 minutes.

How to run it, step by step

1. Divide the group into teams of four to six.
2. Hand each team their kit and read out the rules.
3. Start the 18-minute timer. Call out time warnings at 10, 5 and 1 minute.
4. When time is up, everyone steps back from their structure. Measure from the table to the top of the marshmallow.
5. Announce the tallest standing structure, then move straight into the debrief.

The lesson: prototype early

Teams that win usually test with the marshmallow early, see what fails and rebuild. Teams that spend most of the time planning have no time to recover when the heavy marshmallow buckles their design. It's why young children often beat business school students at this: they start building straight away. The marshmallow is the hidden assumption in every project, the thing that looks light until you actually put it on top.

Debrief questions for managers

The challenge only pays off if you talk about it afterwards. Ask the teams:

1. When did you first put the marshmallow on? What would you do differently?
2. How did your team decide on a design? Who led, and did anyone's idea get lost?
3. What happened when time pressure kicked in?
4. Where in our real work do we plan too long before testing?
5. What is the "marshmallow" in our current project, the assumption we haven't tested yet?

Variations

• Budget version: give teams a budget to buy extra spaghetti or tape. It adds trade-off decisions.
• Leadership version: appoint a silent observer in each team who reports back on how decisions were made.
• Repeat round: run it twice. The second round almost always goes higher, which proves the point about iteration.

Keep the conversation going after the workshop. The Team Conversation Deck gives your team ready-made prompts for the honest conversations an exercise like this opens up, at your next team meeting or offsite.

See the Deck

Marshmallow challenge FAQs

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