How To Teach Fourth Graders Fractions - Math and Reading Help The denominator is the whole that the parts make up. To help students visualize these words, think of it like a pie. Tell them to imagine a pie that is cut into five slices. Then, write an equation: 2/5 + 3/5 = 5/5. Read it as, 'Two of the five slices plus three of the five slices equals all five of the five slices.'