Lesson 4

Measuring Mass

Est. Class Sessions: 2–3

Daily Practice and Problems

Teacher Notes
X

TIMS Bit

These problems can be solved by thinking addition with doubles. (Since 25 + 25 = 50, then 50 − 25 = 25.) However, students will probably solve them in many ways. Ask them to describe their strategies, helping them verbalize their thinking.

  1. 25
  2. 26
  3. 50
  4. 52
  5. 90
  6. 80
  7. Possible strategy: Students may count up from 48 to 50 and then use the double 50 + 50 to find the missing part.
    48 + 2 = 50
    50 + 50 = 50
    50 + 2 = 52

I. Subtraction: Using Doubles

Do these problems in your head. Write only the answers.

  1. 50 − 25 =
  2. 51 − 25 =
  3. 100 − 50 =
  4. 100 − 48 =
  5. 180 − 90 =
  6. 160 − 80 =
  1. Explain your strategy for Question D.