Lesson 5

Subtract Mixed Numbers

Est. Class Sessions: 2–3

Daily Practice and Problems

Teacher Notes
X

TIMS Bit

    1. 7/8

      Closest benchmark: 1
    2. 3/10

      Closest benchmark: 0
    3. 25/12

      Closest benchmark: 21/2
    4. 21/12 = 7/4 or 13/4

      Closest benchmark: 2
  2. Strategies will vary. Possible strategy: both 5/6 and 11/24 are close to 1 so adding them should be close to 2.

Ongoing Assessment

Use DPP item 0 to assess students' abilities to estimate sums and differences [E9].

O. Estimate and Solve

Estimate the sum or difference of each problem below. Choose the closest benchmark. Then solve. Use the pages in the Student Guide Reference section.

0                            1/2                            1                            2                            21/2

    1. 3/4 + 1/8 = Closest benchmark __________
    2. 9/10 − 3/5 = Closest benchmark __________
    3. 12/3 + 3/4 = Closest benchmark __________
    4. 5/6 + 11/12 = Closest benchmark __________
  2. Explain your estimation strategy for Question 1D.