Skills Covered

How to Use This Pack

Five pages on adding and subtracting fractions whose denominators are not the same. Page 1 shows why a common denominator works: dashed lines cut halves and thirds into sixths on fraction strips, so 1/2 + 1/3 = 3/6 + 2/6, and lists of multiples find the least common denominator. Page 2 adds: rewrite both fractions, add the numerators, then write the sum in simplest form, as a mixed number when it is more than 1 (3/4 + 2/3 = 9/12 + 8/12 = 17/12 = 1 5/12). Page 3 subtracts the same way. Page 4 adds and subtracts mixed numbers in columns, trading 1 whole for 12 twelfths when the top fraction is too small. Page 5 checks answers with benchmarks (2/5 + 1/2 cannot be 3/7, because 3/7 is less than 1/2) and has story problems to estimate first, then solve.

In the Classroom

Start page 1 with paper strips: fold one strip in halves and one in thirds, then fold both again until the parts match. Ask why we cannot add halves and thirds as they are. Before page 4, show 4 1/6 as 3 7/6 with fraction pieces so trading a whole makes sense. On page 5, have students estimate out loud before they work anything out.

At Home

Cooking is full of unlike denominators: 1/2 cup of milk and 1/3 cup of water, or 3/4 of a pizza left after eating 1/8. Ask your child to say about how much first, then find the exact amount together.

Tips for Success

• To add or subtract, the parts must be the same size: rewrite both fractions with a common denominator
• The least common denominator is the smallest number both denominators divide into
• Multiply the numerator and the denominator by the same number to make an equivalent fraction
• Simplify the answer, and write an answer greater than 1 as a mixed number
• Estimate with 0, 1/2, and 1 first: the exact answer should be close to the estimate