Estimate and Check for Reasonableness

“When I computed with whole numbers, I always thought that multiplication made the answer bigger and division made the answer smaller. But that is not always true when I multiply and divide fractions.” Mara says.

Fern advises, “I always estimate the product or the quotient so I can tell whether or not my answer is reasonable. Drawing a picture helps, too.”

    1. Estimate the answer to 5 ÷ . Should the quotient be greater or less than 5?
    2. Draw a picture and solve the problem.
    3. How do you know if your answer is reasonable?

Know the Problem and Use Labels

“Sometimes I calculate correctly, but I use the wrong label in my answer,” admits Fern.

  1. Read the problem below carefully. Think about what the question is asking you to find out and show how you solve the problem. Use a label to show what the numbers in your answer mean.
  2. There is of a bag of beads. How can 3 children split the beads equally?

Use the Self-Check Questions in the Student Guide and the Workshop Menu on the Find Fraction Products and Quotients pages in the Student Activity Book to help you choose practice multiplying and dividing fractions.