Lesson 5

Earning Money

Est. Class Sessions: 2

Daily Practice and Problems

Teacher Notes
X

TIMS Task

Discuss the variety of strategies students use to solve these problems.

  1. Possible response: After Joe multiplied 20 × 6 = 120, he added in 6 more to get 126. That is the same as 20 × 6 + 1 × 6. He should have subtracted 6 to get the answer 114. The problem is 20 × 6 − 1 × 6 = 120 − 6.
  2. Possible responses: You can multiply 30 × 3 − 1 × 3 = 90 − 3, or 87; or you can multiply 20 × 3 + 9 × 3 = 60 + 27, or 87.

R. Joe and Moe Smart

Joe Smart's answer for the problem 19 × 6 was 126. Moe Smart got a different answer. Joe said, “Well, first I did 20 × 6.” Moe said, “I agree with that, but …”

  1. Finish Moe's statement explaining to Joe what he did wrong.
  2. Tell how you can find 29 × 3.