Lesson 1

Strategies for Subtraction Facts

Est. Class Sessions: 2–3

Daily Practice and Problems

Teacher Notes
X

Ask students to share their solution strategies. Have base-ten pieces readily available.

  1. 250 is closest to one-half of 505. Students’ strategies will vary. You may suggest or model using a number line to make an estimate.


    2. Students can easily see that of the three choices, 250 is the closest to about half of 505.

  2. Estimates should be reasonably close to:
    1. 150
    2. 90
    3. 225

B. Number Sense and Estimation

  1. Roberto has 505 baseball cards in his collection. He keeps about one-half of them in a secret place. About how many cards might he have hidden: 100 cards, 250 cards, or 400 cards? Explain your answer.





  2. What number is:
    1. About one-half of 305? __________________________
    2. About one-half of 181? __________________________
    3. About one-half of 450? __________________________