Students across Driscoll enjoy the Which One Doesn’t Belong routine. In this routine, four images (or numbers or graphs) are displayed, and students are asked to select which one of the four does not belong with the other three. This routine “fosters a need for students to identify defining attributes and use language precisely in order to compare and contrast a carefully chosen group of geometric figures, images, or other mathematical representations.” (from the Illustrative Mathematics alpha pilot teacher materials) If you’re interested in learning more about this routine, including example from Driscoll classrooms, read this blog post from October 2019.

This week, fifth graders engaged with the following Which One Doesn’t Belong task, from the first unit of IM K-5 Math (a curriculum we have been piloting all year).

Students shared their responses using the website Padlet. There were reasons for why each of the 4 shapes did not belong with a group of the other 3. For example, some students said that figure A didn’t belong because:

Students said that figure B didn’t belong because: