What is the Marshmallow Tower Challenge?
The Marshmallow Tower Challenge is a 45-minute team exercise where students build the tallest freestanding structure they can from spaghetti, tape, string, and one marshmallow, then rebuild it after a short debrief.
In an entrepreneurship course it is a concrete analogy for how unvalidated assumptions cause startup failure, and how rapid iteration beats extended planning. This guide includes the updated rules, a free lesson plan, and a reflection worksheet.
Free Marshmallow Challenge reflection worksheet
After the build, have students reflect online on what their tower taught them about assumptions and iteration. Use our free digital reflection template, or download it as a printable PDF.
This revised version of the Marshmallow Challenge is a really fun way to teach the importance of iteration, experimentation, and the value of failure.
This updated exercise will help your students learn:
- Why hidden assumptions hinder entrepreneurs
- How iteration and experimentation weed out hidden assumptions
- Why business experiments replace business plans
Note: if you’re already familiar with the Marshmallow Challenge, here are the key updates in this version:
- This exercise isn’t just about team building or ice-breaking; it’s an analogy for business model assumptions, experimentation, and iteration.
- Teams build towers twice: once to discover that they make hidden assumptions and once to resolve them.
- There is a minimum height requirement to ensure students push their limits (and reinforce the learning objectives).
- As homework, students write a short reflection on the dangers of hidden assumptions and the benefits of fast experiments and iterations.
Step 1: The Set Up
Students work in teams of four to build the tallest tower they can using only the provided materials.
Step 2: Build, Launch (and Fail!)
With only 18 minutes to build their towers, teams often follow a similar construction timeline:
- ~3 minutes: Figuring out who is in charge
- ~10 minutes: Planning
- ~4 minutes: Taping spaghetti together
- ~1 minute: Putting their marshmallow on top
- ~1 second: Watching the tower crumble under the (surprising) weight of the marshmallow
Be sure to strictly enforce the rules and not give students tips.
The point of this first iteration is for students to experience the failure that comes from not testing their assumptions
For example, students often assume:
- Marshmallows are light
- Uncooked spaghetti is rigid enough to hold up a marshmallow
Most of the time, students find out these assumptions are incorrect far too late into the exercise to do anything to correct them.
Finish this step of the lesson by asking students what assumptions they made that may have led to their failure. Then ask them, “Do you know who doesn’t make these kinds of assumptions?”
Step 3: Kindergartners
Tell students that this exercise has been completed by a wide range of people and the average tower height is 20 inches tall.
What’s most interesting is that some people consistently perform better. While business school students often struggle, there’s one group of students who do particularly well:
Kindergartners!
Then show a slide like this to your students:
Why Do Kindergarteners Build Better?
First thing: let your students know it’s not their fault – there’s nothing inherently wrong with them. They just made the mistake that virtually every first-time entrepreneur makes:
“You made assumptions about the world that turned out to be wrong.”
In the entrepreneurial context, that typically means making assumptions about who your customers might be, how much they’d be willing to pay for your product, and how many of them there are.
In this case, assumptions about their building materials led to sub-optimal performance, but why would kindergartners be able to build better towers than they could?
Because kindergartners don’t make assumptions!
Kindergartners don’t know that marshmallows are supposed to be light and uncooked spaghetti is supposed to be rigid, so the first thing they do is stick the marshmallow on the spaghetti and see what happens.
In other words, kindergartners don’t know enough about the world to make assumptions so instead of “planning” they naturally spend their time experimenting and iterating.
Tell your students that whenever they’re doing something they’ve never done before (e.g., launching a new product), the best way forward is often to run quick experiments so they can discover the hidden assumptions they’re making.
Once they’ve discovered their hidden assumptions, they’re ready to test out different solutions, which leads us to . . .
Step 4: Iteration
Now that they’ve had a chance to discover their hidden assumptions it’s time to let students act like kindergarteners and iterate and try again!
Give your students another set of supplies and let them build again. When they’re finished, compare the results of their first and second iterations. Use this as an analogy for:
- Why serial entrepreneurs are often more successful than first-time entrepreneurs
- Why business plans are often replaced by business experiments (e.g., quick experiments lead to more, faster, and validated learning than business plans).
Florida State University students in Ron Frazier’s class
Step 5: Reflection
Have students capture their reflection in the free interactive reflection worksheet with no sign-in, or print a blank copy for class.
After class, ask students to write up a reflection on the difference between writing business plans and running business experiments:
- When would they want to use a business plan?
- When would they want to use a business experiment?
- Why?
What if Your Students Have Already Done It?
It’s not uncommon for students to have done a version of the Marshmallow Challenge in another class. That said, they likely did it as an ice breaker or team-building exercise – not with a focus on iteration and experimentation.
Ask any students who have done this previously to form their own team of “experienced builders.” This will enable you to reinforce the learning objectives no matter how tall their towers are:
- If the experienced teams build successful towers, you can point to them as examples of the power of iteration (their previous iteration being the first time they did the exercise)
- If the experienced teams do poorly, you can cite how important it is to keep practicing the power of iteration throughout our careers – it’s an easy lesson to forget!
Get the Updated Marshmallow Challenge Lesson Plan
We’ve created a detailed lesson plan for the “Updated Marshmallow Challenge” exercise to walk you and your students through the process step-by-step.
It’s free for any/all entrepreneurship teachers. Please feel free to share it.
FAQ: Teaching the Marshmallow Tower Challenge
What is the Marshmallow Tower Challenge?
It is a team exercise where students build the tallest freestanding structure they can from spaghetti, tape, string, and one marshmallow, then rebuild after a short debrief. It runs in about 45 minutes.
What does the Marshmallow Challenge teach entrepreneurship students?
That unvalidated assumptions cause failure, that rapid iteration beats extended planning, and that failure is useful data. It is a concrete analogy for testing the riskiest assumptions in a business model before committing resources.
What materials do you need for the Marshmallow Challenge?
Each team of about four students needs roughly 20 sticks of uncooked spaghetti, one yard of tape, one yard of string, and one marshmallow. There is no practical limit on class size; just run multiple teams at once.
How long does the Marshmallow Challenge take?
Plan for about 45 to 60 minutes total, including the first build, the kindergartner debrief, the second build, and a written reflection.
Is there a free lesson plan and reflection worksheet?
Yes. The updated lesson plan with slides and facilitator notes is linked on this page, and a free interactive reflection worksheet is available for your students.
Attribution
The original version of the Marshmallow Challenge comes from Tom Wujec. Here are his original instructions and associated TED Talk.
A version similar to the original exercise was also published by Bradley George:
George, B. (2014). Marshmallow Tower. In H. Neck, P. Greene & C. Brush (Eds.), Teaching Entrepreneurship: Challenging the Mindset of Entrepreneurship Educators (p.125-130). Northampton, MA: Edward F. Elgar Publishing.
What’s Next?
In upcoming posts, we will share more exercises to engage your students.
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