Which One Doesn't Belong? Ways to Make Five

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 train of 3 green and 2 orange cubes. The equation is 5 = 3 + 2. B: A ten-frame holds 3 blue dots and 2 red dots. The equation is 3 + 2 = 5. C: A train of 3 blue and 2 red cubes. The expression is 3 + 2. D: A train of 4 blue and 1 red cube. The equation is 4 + 1 = 5.


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?