Three Acts

This instructional routine is intended to support students in using mathematical modelling to solve contextual problems and to learn how to have mathematical discussions with each other. It was created by Dan Meyer.

In the routine students are prompted to develop a mathematical question, generally through the use of a video or photo to pique their mathematical curiosity. Students are asked to provide a “just right” guess as to the solution, then determine what they need to know to solve the problem. Students then work to create a solution to the problem and finally the answer is revealed, again through the use of multimedia.

The flow of the instructional routine is

Orient to the task:

  1. Launch: (1 - 2 minutes)

Tell students why they are doing this activity and how the activity will run.

Develop a Question:

  1. Individual Think Time: (10 - 30 seconds) 

  2. Pair-Share: (1 minute)

Students look at an example of multimedia, share their possible questions with a partner. 

Share Questions:

  1. Full group share: (4 - 6 minutes)

Selected pairs of students share their questions with the whole class. Students are then prompted to consider an answer that is too low, an answer that is too high, and a “just right” answer to one of the questions.

Model the Problem:

  1. Think & Pair: (3 - 10 minutes)

Students develop a model for the problem, asking for more information if they feel they need it while the teacher circulates around the room.

Share Solutions:

  1. Share: (4 - 8 minutes)

Selected students share their solutions to the problem and then the answer is revealed.


  1. Individual writing: (1 - 2 minutes) 

  2. Pair: (30 seconds) 

  3. Share: (2 - 3 minutes)

Students write independently, students share what they wrote with a partner, then selected students share their reflections with the whole class. 

Learn more about the routine:


  1. Sample Slides

  2. Sample Tasks

Adapted from Dan Meyer’s blog and Teacher Education by Design:

Last modified: Wednesday, 21 August 2019, 8:39 AM