Which One Is Unique?

  • What is Which One is Unique?

    Which One is Unique? is a short routine where students are asked to look at four images and share their reasoning about which image they think is unique. This routine was formerly referred to as Which One Doesn’t Belong. Based on teacher feedback, the name and language around this routine was adapted to align with our work in Portland Public Schools around inclusiveness. (Please note, if you want to search online for resources around this routine, use the title, "Which One Doesn't Belong")

    As with other Math Talk routines, there are many possible responses. The focus is on students being able to communicate their reasoning and justification for their choice.  Students are encouraged to think of more than one response or multiple reasons for the same response.


    General Outline for Which One is Unique?

    1. Post the image for all students to see.
    2. Allow wait time for students to consider which one they think is unique and their reasoning. 
    3. Have students share their choice. Here are some possible ways you might have students share their initial choice:
      • Teach students the sign language for A, B, C and D. Then when you give the signal, they show the hand sign for their choice. 
      • Assign a letter in 4 corners or locations in your room. On your cue, students move to the location corresponding with their choice.
      • Students write their choice on an individual white board, and on your cue, they hold up their white boards. 
    4. If possible, provide time for students to talk with a partner (or small group) about their choice and their reasoning.
    5. Select a student to share their rationale for their choice.
    6. Encourage students to ask questions, revoice and rephrase in order to fully understand each other's thinking. 
    7. Ensure that at least one student shares for each possible choice.
    8. As time and interest allows, have students share varying reasons for each choice.
    9. To close, ask students to reflect on new learning.

    Some questions you might ask are:

    • What do you notice?
    • How are all the images alike?
    • How are they different?
    • Which one do you think is unique?
    • Why do you think that one is unique?
    • What is a different one that is unique? Why?

    Additional resources you might find helpful: