Which One Doesn't Belong? Adding Fractions

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!

In A, a strip model shows one-half + two-fourths. In B, a strip model shows one-third + two-thirds. In C, an egg carton model shows six-twelfths + six-twelfths. In D, a strip model shows three-fifths plus three-fifths.


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?