Great Classroom Action


Christina Tondevold teaches her first three-act math task. There’s a lovely and surprising result at the end, when her students realize that with modeling the calculated answer doesn’t always match the world’s answer exactly.

After they all had taken the 24 bags x 26 in each bag, every kid in that room was so confident and proud that they had gotten the answer of 624, however … the answer is not 624! Why do you think our answers might be off?

John Golden creates and implements a math game around decimal addition called Burger Time with some fifth graders:

Roll five dice to get ingredients for your burger. The numbers correspond to how many mm tall each part is.

Matthew Jones creates a Would You Rather? activity and one of his “defiant” students makes an effective justification of a counterintuitive choice:

He blurted out “I want to paint Choice C.” I told them at the beginning that there was no right/wrong answer, they just had to justify it. I was lucky enough that he thought of the reason why you’d want to paint the larger one. The only reason you’d want to paint the largest wall is because you are paid by the hour. It was really interesting watching him come to that conclusion. And to take pride and ownership in the way that he did.

Jennifer Wilson describes one of NCSM’s “Great Tasks” and shows how she gathers and sorts student work with a TI-NSpire.

Students are asked to create a fair method for cutting any triangular pizza into 3 equal-sized pieces of pizzas. I asked students to work alone for a few minutes before they started sharing what they were doing with others on their team. I walked around and watched.

I'm Dan and this is my blog. I'm a former high school math teacher and current head of teaching at Desmos. He / him. More here.


  1. Thank you for the mention, Dan. As I’ve done that task multiple times now, I’ve noticed how each group does come up with my intended question. However, the other questions they come up with seem to be dependent upon the content they have been recently working with. For instance, the last group of 5th graders that I gave the Cheese Balls task to came up with a bunch of questions around the idea of Volume. So the teachers and I have been wondering when is the appropriate time to do 3 Act Math tasks? Our consensus is that “it varies” depending upon many scenarios we came up with…but would love your thoughts.

    Thanks again,

  2. @Christina, I love hearing student questions because it reveals a lot to me about their curiosities. I don’t need their questions to match the question I’d like to ask them.

    Asking for their questions and asking them my question serve two different purposes.

    Asking them my question orients us all in the direction of the same mathematics.

    Asking for their questions helps them start to engage with the scenario, gives me a chance to learn about their curiosity, and offers us questions we can choose (or choose not) to take up later.