The Tower

This post is part of the 2011 Virtual Conference on Core Values hosted by Riley Lark. The prompt for the conference is “What is at the center of your classroom?” You can see the rest of the blog entries in the conference at the Virtual Convention Center.

What is at the center of my classroom? It’s not an interactive whiteboard. It’s not an angry bird. It’s not a Sal Khan dart board. It’s a tower. A tower which represents success, failure, and risk-taking. The tower is built from uncooked spaghetti, tape, and string. It is unimpressive and crude, perhaps leaning to one side while a marshmallow rests at the top.

Surely you’ve seen this tower before. Perhaps you and/or your students have built one. It’s from The Marshmallow Challenge, a great team-building activity. Using 20 pieces of spaghetti, 1 meter of tape, 1 meter of string, and 1 marshmallow, teams try to build the tallest free-standing tower that will hold the marshmallow on top. Time is limited to 18 minutes.

Tom Wujec gave a great TED talk about the challenge. It’s only 7 minutes long, and well worth your time.

Wujec talks about collaboration, skills, and hidden assumptions. Some teachers use the challenge on the  first day of school to be different from their colleagues who lecture about syllabi and rules. For me, however, the tower lives on throughout the year and becomes a symbol for the core value at the center of my classroom.

You see, the unsuccessful teams typically wait until the 18 minutes are over before putting the marshmallow on top. In contrast, the teams that successfully build a tower which can support the marshmallow typically go through several cycles of building and testing during the 18 minutes. Build, test, modify, retest, repeat. It’s a feedback loop.

So where does the feedback loop appear in my classroom?

The Feedback Loop in Science

Modeling Instruction is the framework for much of my instruction. A modeling cycle typically consists of two stages: Model Development and Model Deployment. During the model development stage, students are designing experiments to determine the model that governs a specific scenario (e.g., a battery-operated car moving at a constant velocity). During the deployment stage, students apply their model to other scenarios, use it to solve typical physics problems, and perform a lab practicum (e.g., predict when and where two different battery-operated cars will collide).

Often, the model will need to be refined. For example, here’ s how Matt Greenwolfe does the constant velocity lab:

I do the buggy lab twice.  The first time, it’s a distance vs. time lab and the resulting graph does have a zero y-intercept and its slope is speed. This is the way the students intuitively approach the lab anyway – measure distance and time.  The second time, I make sure there are issues of starting point and direction of motion and we do position vs. time and the slope is velocity –  the motivation being that this can describe more aspects of the motion than distance vs. time graphs and speed.

Sometimes the model completely fails. For example, the constant velocity model can’t help us predict the motion of ball rolling down a ramp. So we start the cycle over again and develop a new model, often seeing connections between them.

The Feedback Loop in Learning

Standards-based grading is the feedback loop while traditional grading waits until the very end to give feedback (which by that point is useless). When students track their progress, they see the feedback loop in action. Just like building the tower, all the “failures” are necessary feedback to help students succeed.  And since SBG doesn’t penalize students for those initial failures, students feel more comfortable taking risks.


Whiteboarding is another great way for students to get just-in-time feedback from you and from peers. While collaborating in small groups, students are discussing and sharing their ideas and solutions. Likewise during whole class presentations and discussions. Because whiteboards are easily erasable, students are more likely to take risks when solving problems, than using chart paper or a worksheet. For more details, see Tomas Ro’s great post Whiteboards vs. Chart Paper.

The Feedback Loop in Teaching

My classroom is a spaghetti tower itself. I am fortunate to have supportive administrators who understand the need to experiment and explore new lessons and methods. I make sure to let my students know when we are trying something new — I want them to see me as a learner, too. I frequently ask my students for their feedback. I don’t collect dashboard data, but real and useful information via concept inventories, informal questioning polls, and more formal surveys.

The Take Away

In the Marshmallow Challenge, the successful spaghetti towers would not be possible without continuous testing and failing. That is why success and failure must be celebrated with equal enthusiasm and that as teachers we must encourage continuous risk-taking.

Where is the feedback loop in your classroom?

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21 responses to “The Tower

  1. I’ve done the tower using paper and paper clips, but I like what the marshmallow represents. Consider this stolen borrowed.

  2. This is great. I’m a student in engineering school right now, and I do a lot of project work where iteration is really emphsized (and crucial for success), so this post really hits home for me.

    I frequently work with elementary and middle school students, introducing them to engineering through hands-on activities. (I’m planning on becoming a teacher.) A lot of the activities we do are design challenges, where we really try hard to get the kids to iterate on their designs. There’s a class of 6th graders that I work with weekly throughout the year, and watching the TED talk got me thinking that maybe it would be good to do this activity the first week, show them the TED talk and discuss that. Then throughout the year, as they’re doing different activities, it can be a discussion we come back to, to hopefully get the kids more comfortable with iteration and the design process. What do you think: would that be a good way to set the stage? Or will the discussion only really have meaning to them later, once they’ve had more experiences to relate it to?

    • I think that since iteration typically happens within the 18 minutes, it is good way to start the year. Perhaps running it again with different groups the next day might be useful — how will the kids take their expertise from the first round (along with the winning and not so winning designs) to make their new towers even better?

  3. Frank,
    Great post. I’d like to use the Marshmallow Challenge this year myself. Sounds so great for team building and reflecting on process, the latter being the real hidden zinger.

  4. One way to get students to iterate their designs is to give the same assignment repeatedly on subsequent days, telling them that they have to have at least one “improvement” from their previous attempt. I don’t do this repetition with design projects (though it is something worth trying), but in many of my classes there are drafts of the final paper due every 2 weeks, and each draft is supposed to incorporate all the feedback from the previous draft.

  5. “where is the feedback loop?” — great question. I feel like you’re personally challenging me to prove that students are getting the feedback they need. food for early august thought.

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  9. Great post, Frank. This resonated with me on both the student level and the teacher level. I’m always struggling in my CS classes with students who expect to know the right answer the first time, and can’t abide with a coding process which necessarily requires iteration. And as a teacher, I always feel like my lessons are in constant beta, always changing and evolving. This post is inspiring me to go post something on my teaching blog — thanks!

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  14. Oh my gosh. I literally spewed coffee when I read the “It’s not a Sal Khan dart board.” remark. I’ll be laughing at that one all day! LOVE.

  15. I did the same. Great idea for starting off the new year. Thanks, Frank.

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  20. Lots of food for thought. Love that you’ve provoked me into asking myself “what is at the center of my teaching?” Added you to my blog reader over on Ms. Z Teaches in Mathland. Thank you.

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