3rd Grade Adding and Subtracting Like Fractions Worksheet: Eight Sums

When two fractions have the same bottom number, adding them is almost as easy as adding whole numbers. This 3rd grade adding and subtracting like fractions worksheet has eight items, numbered 1 to 8, in two columns on grid paper. Items 1, 3 and 5 are sums, such as 2/7 + 3/7, while the other five are differences, such as 15/10 - 7/10. Every pair in an item shares the same denominator, so your child only works with the top numbers. The instruction also asks them to simplify each answer. Two scouts sit by a campfire at the top, and a girl with binoculars waits at the bottom. Page two writes out every step and puts the final answer in a pink box.

Eight answers to check

The boxed answers are 5/7, 4/5, 7/15, 13/30, 1, 1/8, 1/5 and 3/10. In item 2, 8/10 simplifies to 4/5, and in item 5, 14/14 makes one whole. All the boxed answers in the key are right.

The key tells your child to add or subtract the numerators only, because the denominators are the same. That one idea is the heart of the whole page, and every item uses it in exactly the same way. Note that adding fractions with like denominators is a fourth grade standard, and simplifying comes even later, so this page is a big stretch for third grade.

At the table: keep the bottom number

A common mistake is to add the bottom numbers too, so that 2/7 + 3/7 turns into 5/14. Ask your child to cover the denominators with a finger, then work only with the top numbers. Next, they write the same denominator under the answer. Subtracting fractions works the same way.

The key has a small mismatch. At the top of items 5, 7 and 8, it shows 14/14, 5/25 and 6/20 without simplifying them, while item 2 shows 4/5 straight away. The boxed answers at the bottom of each item are all simplified, so use those boxes when you check your child's work. The title also ends with a stray full stop.

After the page: pizza slices

Draw a pizza cut into 8 equal slices and colour 3 of them. Then colour 2 more and ask your child how many eighths are coloured now. Next, rub out 4 slices and ask again. Finally, check the eight answers with the answer key on page two.