3-Act: Super-Sized Coffee

This was the first lesson I did to start off my practicum. It’s entirely based on a 3-Act Task by Dan Meyer. Originally, I had my lesson set-up inline with the task to target the question: How many gallons of coffee would it take to fill up the super-sized cup? 

Walking through the plan with my mentor, however, she noticed that the students might be quick to solve this one—given that they had some similar practice before—and suggested that we start with the extension question instead: How many regular-sized cups of coffee would it take to fill up the super-sized cup? This would also offer them a new challenge during the conversion process.


What I appreciate the most about great mentors is that feedback is always offered with choice. Even though my plan was fully written-out and I was now playing around with my slides on Pear Deck 20-minutes before I walk into my lesson, the decision to change the plan was still mine to make. Of course knowing that your mentor will be there to back you up when you need the support makes risk-taking much easier.

Moving on, I presented the entire task via Pear Deck here (full credit to my AT, for showing me how to properly set-up a 3-Act Math Task on Pear Deck and choice of wording).

ACT 1: Gourmet Gift Baskets Video (making/filling-up the super-sized cup) followed by: wonder

So, “why are they wasting coffee?” To try and set a new world record! But before finding out if they were successful or not, we focused on, “how many average cups could fill the large cup?” We estimated numbers that are too high, too low, made a best guess, and then it was time to solve.

ACT 2: What information do we need to help us solve?

I presented the image of the super-sized cup along with its dimensions on the screen, and acting on another pro-tip, I simply placed my Starbucks coffee cup on a high table—front and center—and left it up to the students to get their own measurements. Most measured in centimetres, but one group went with inches instead. They worked on this task in VRG on VNPS.solving

All groups applied the right formula to find the volume of the super-sized cup and average cup but ended-up with different numbers. With support from my AT, here’s what we discussed:


1. The top diameter of the Starbucks coffee cup is 8cm and the base diameter is 6cm. We had to take this into consideration to get a more accurate sense of how much coffee can actually fit inside the small cup. One of the students suggested that we take their average and so we did.

2. Most students aimed to convert the volume of the large cup into centimetres, but did a length conversion instead. My AT highlighted the difference and then we talked a little about the method of operation they used to solve (subtraction vs. division). It was then time to wrap-up the lesson. error-conversion

The following day I asked two of the students to use the portable keyboard available in the classroom to explain and model the steps for converting volume before sending them back to their boards to finish solving.

Here are some of the answers we got:answer_coffee20161108_115943

ACT 3: Video result (available in Pear Deck link): were they able to set a new world record/how many gallons of coffee is that?

We didn’t actually get around to watching the video result mainly because it took me sometime to get a good handle on time management during practicum, but we worked on a consolidation handout to allow for individual reflection/practice on conversion—which is the area I found they struggled with the most.

Overall, I really enjoyed this task and one that I would definitely try again. I felt it was really rich in its content and offered students a nice visual to develop their conceptual understanding of volume and conversion. Time management and better preparation to be able to offer strategic support during productive struggle will be my areas of improvement for next time.