Subtracting Fractions with Unlike Denominators

Give a short warm-up on common denominators first, then the sheet. Twenty problems take roughly twenty minutes. Suggest writing each converted fraction on a second line so the subtraction is easy to see. Because the larger fraction always comes first, students never have to deal with a negative result. Check with the answer key, and look at answers that are correct but unreduced. You can print five versions for a pair of tests.

The skill is the same as adding unlike fractions, with one more risk: subtracting numerators and denominators straight across. A problem such as 3/4 minus 1/6 needs twelfths, so both fractions change before anything is taken away. Both fractions are proper, so no borrowing from mixed numbers appears; that comes later. Students who are fluent at comparing fractions and at converting to equivalent forms do best. After this page, mixed number subtraction is the natural step.

Up to 6 limits the work to small denominators, which suits a first attempt. Up to 12 includes pairs like 5/12 and 3/8 that need careful factor work. Twelve problems per page give room for neat steps. To check, ask the student to add the answer to the subtrahend and see the first fraction come back. Missing number mode turns this into a short puzzle.

Do students need to figure out which fraction is larger?

No. The larger fraction is always first, so each answer is positive. If you want that step practiced as its own skill, the comparing fractions page is the place.

Are mixed numbers used on this page?

No. Both fractions are proper, so there is no borrowing from a whole number. That skill is harder and comes after students handle common denominators comfortably.

What goes wrong most often?

Children subtract tops and bottoms separately, so 3/4 minus 1/6 becomes a nonsense fraction. A quick fix is to say: same-sized pieces first, then subtract. Keep a model bar nearby.