The Marshmallow Challenge: Rules, Kit List and What It Teaches Teams

The marshmallow challenge is the most efficient team building activity ever invented. It costs about $15 a team, needs 18 minutes and one table, works with four people or four hundred, and consistently exposes the same thing: who in the group plans and who in the group builds.

It is also the most commonly run activity where the rules get muddled, which is why half the spaghetti and marshmallow towers on the internet were built under three different sets of instructions. Here are the rules we use, the kit list, the scoring, and what to say in the debrief.

What is the marshmallow challenge?

Teams of four get 20 sticks of spaghetti, one metre of tape, one metre of string and one marshmallow. In 18 minutes they build the tallest free-standing structure they can, and the marshmallow has to sit on top. Nothing may hang from above, and nothing may be taped to the table.

The marshmallow is the point. Most groups spend 17 minutes building an impressive spaghetti tower and 60 seconds discovering that a marshmallow weighs more than their structure can hold. Teams that put the marshmallow on top early and rebuild repeatedly almost always end up taller.

The rules (and why the 18 minutes matters)

•Teams of four. Larger groups work in pairs inside the team, which is a different exercise.

•Each team gets 20 sticks of spaghetti, 1 metre of string, 1 metre of masking tape and 1 marshmallow.

•18 minutes of build time, timed out loud. Announce the 12, 7, 5, 3 and 1 minute marks.

•The structure has to be free standing at the end. No props, no leaning on a wall, no tape on the table.

•The whole marshmallow goes on top. No biting, no cutting, no skewering it onto a stick that then holds it up.

•Measure to the top of the marshmallow, after ten seconds of standing without being touched.

The 18 minutes is not arbitrary. It is long enough that planning feels affordable and short enough that planning for too long is fatal, which is exactly the lesson you want from a 20-minute exercise.

What you need: the kit list

•Spaghetti: 20 full-length sticks per team. Buy the cheapest long spaghetti you can find; it behaves the same and it breaks the same.

•Masking tape: one metre per team, pre-measured and stuck to the table edge if you want to stop the tape debate.

•String: one metre per team, pre-cut. Cotton string is easier to tie than slippery synthetic.

•Marshmallows: one standard marshmallow per team, plus spares for the inevitable. Do not use the giant ones unless you want every tower to fail.

•A tape measure and a table each. Space matters more than equipment: teams need room to stand up and reach around their structure.

•A timer. Loud and visible.

Total cost is roughly $15 a team from a supermarket, and it packs into a shoebox. That is the reason it is still the default indoor team building activity twenty years after it became famous.

How to score it

Measure every tower, then award three prizes rather than one. Height alone rewards luck, and the other two categories are where the learning is.

•Tallest tower that stands unaided for ten seconds with the marshmallow on top.

•Best failure: the team whose tower collapsed most dramatically, given generously and deliberately, because it rewards prototyping.

•Best process: the team that tested the marshmallow earliest, judged by the facilitator watching rather than by height.

What the marshmallow challenge teaches

The debrief writes itself once you have watched a few rounds, because the same four patterns show up every time.

Planning versus prototyping

Groups that argue about a design for nine minutes rarely beat groups that build three bad versions in the same time. In the work world that is the difference between a project that discovers its risk in week two and one that discovers it the day before launch.

The marshmallow is the hidden requirement

Teams treat the marshmallow as the finishing touch and the spaghetti as the real work. Real projects usually have one small requirement that turns out to govern everything, and it is almost always the thing nobody put in the plan first.

Who gets to touch the structure

Watch for the person who has not touched a stick in ten minutes and the person who has not let go of one. Both are useful data for the team, and both are easier to raise after an activity than in a performance review.

Resource constraints produce clarity

Twenty sticks and one metre of tape sounds restrictive until the group realises the constraint is what makes the decisions fast. Give teams unlimited spaghetti and the exercise stops working.

Variations for bigger groups and shorter sessions

•Under 30 minutes total: 12 minutes to build, 8 minutes to debrief. Skip the prizes if you are tight.

•Over 100 people: run it in tables, then have the top three towers judged on stage by someone senior. The judging gets a laugh and takes two minutes.

•Anyone can win: add a rule that the structure must survive a light fan test, which stops teams building a single vertical stick.

•Conference plenary: run it as a table challenge with points that count towards a conference-long leaderboard, so the 20 minutes keeps working all day.

•Online teams: hard to do remotely, but a virtual version works where each person builds from their own kit on camera and the group votes on height from screenshots.

Marshmallow tower, spaghetti tower and pasta tower: is it the same thing?

Yes. The marshmallow challenge, the spaghetti tower challenge, the spaghetti and marshmallow tower, the marshmallow tower challenge and the pasta tower challenge are all names for the same activity with the same rules. Some versions swap spaghetti for dry pasta, which changes nothing except that the structure is slightly shorter and the floor slightly messier. If you are searching for any of those names, the rules above are the ones to use.

How to debrief it in five minutes

Ask four questions in this order and stop talking.

•What was the first thing your team did when the clock started?

•At what point did the marshmallow go on top?

•What did the group assume about the marshmallow that turned out to be wrong?

•What is the equivalent of the marshmallow in your current project?

That last question is the entire reason to run the activity. If the answers are specific and uncomfortable, it worked.