February 17, 2021

Which One Doesn't Belong (WODB)


Which One Doesn't Belong (WODB) is an instructional routine to help students deepen their mathematical thinking and build a growth mindset.


1. Math Practice 3

The various state content standards are WHAT we teach in math and the Standards of Mathematical practice are HOW we teach math. These practices are based in research and strive to help students become problem solvers and critical thinkers. Math Practice standard 3 is about constructing viable arguments and critiquing the reasoning of others. WODB gives students an opportunity to explain their reasoning and evaluate the reasoning of their peers.

2. Encourages a Growth Mindset

Carol Dweck's research has found that most people have one of two mindsets: fixed or growth. If you aren't already familiar with Growth Mindset, check out the quick overview video below. In a blog post by Mike Anderson he points out some math misconceptions that are worth considering as well. Basically though, students who believe that math is a "you have it or you don't" type of subject are less likely to persevere in problem solving and ultimately less likely to succeed. Student who believe that math is an area where they can learn and grow, those with a growth mindset, are most successful.

3. Supports Expressive Language

Expressive language is used to convey meaning and messages to others. Along with receptive language, this is a vital skill for children. Students need opportunities to articulate their thoughts and ideas throughout the day to support this, not just in reading or language arts classes. This discussion in mathematics is critical to both conceptual understanding and to the students' ability to express themselves.


We ask students to follow the same series of steps each time this strategy is used in order to make it routine. Routines support a growth mindset as well by reducing threats and distractions - they know what to expect.

  1. Look at all of the images
  2. Decide 'Which One Doesn't Belong'
  3. Pair Share - tell a partner which one doesn't belong
  4. Whole Group Share
  5. Reflect - explain someone else's thinking

Dig Deeper

Ideas for Strategy Use

This strategy lends itself so well to both a face-to-face and a virtual format.

Four Corners
When in a face-to-face format you can incorporate physical movement and turn this into a 4 corners activity. You would label each corner with a letter - A, B, C or D. Then students go stand in the corner for the letter associated with the image that doesn't belong. This is also a great opportunity for students to discuss with others who chose the same image they did. They may discover that someone chose the same image, but for a different reason! Then students can share out with the whole class.

Dry Erase Boards
Whether face-to-face or online students love dry erase boards! You have them just write their letter on the board, or you can have them include their reasoning. Then students can hold up their boards to the camera or to the class to show others their choice and spark discussion.

Do Now, Morning Work or Exit Ticket
WODB also makes for a great low floor high ceiling task that lends itself to do now or morning work activities at the start of class. Students can immediately come in and respond in a chat virtually, in a journal, on a sticky note or on a dry erase board. Sticky notes can be used to create a visual of how many students chose each one when added to a front board or poster. Likewise you can use this as an exit ticket out the door.

Leave a Reply

Your email address will not be published. Required fields are marked *

linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram