Lesson 7

Workshop: Addition and Subtraction

Est. Class Sessions: 1

Daily Practice and Problems

Teacher Notes
X

TIMS Task

  1. Estimation strategies will vary.
    1. A. 3920; 4400 − 400 = 3900
    2. 5147; 5200 − 100 = 5100
    3. 3389; 4300 − 1000 = 3300
    4. 30,497; 34,500 − 4000 = 30,500

  2. A possible strategy for problem A:
    56 − 36 = 20 (counting by tens up from 36, 46, 56)
    4300 − 400 = 3900 (counting back)
    3900 − 20 = 3920

    A possible strategy for problem D:
    34,000 − 4000 = 30,000
    500 − 3 = 497
    3000 − 497 = 30,497

Z. Subtraction

Use a paper-and-pencil method or mental math to find exact answers to these problems. Show how you estimate to see if your answers make sense.

  2. Explain your strategy for a problem you solved using mental math.