Which One Doesn’t Belong? We Are Many Parts

Look at this set of four pictures. Decide which one doesn’t belong with the other three. Use math words to describe your thinking. There are many ways to think about each one!

A: A geoboard rectangle has 8 equal square parts. 1 part is green. B: A geoboard square has 4 equal triangular parts. 1 part is purple. C: A geoboard rectangle has 4 equal rectangular parts. 3 parts are yellow. D: A geoboard rectangle has 4 parts. Two parts are squares of the same size and 2 are rectangles of the same size. 1 square is blue.


See if you can find reasons why each of the pictures might not belong with the other three.


Explain your thinking to someone else. Do they have different reasons why one doesn't belong?