Lesson 3

Button Sizer

Est. Class Sessions: 1–2

Daily Practice and Problems

Teacher Notes
X

Model each problem on a display using buttons or other counters.

  1. 30 − 20 = or
    30 − = 20; 10 buttons
  2. 25 − 10 = or
    25 − = 10; 15 buttons

I. Hidden Buttons

Solve and write a number sentence.

  1. Martha placed thirty buttons on a display. Then she covered twenty of the buttons with paper. How many buttons were still showing?


    Number sentence ___________________________________________________

  2. Charlie placed twenty-five buttons on a display. He covered some buttons. Ten buttons were showing. How many did he cover?


    Number sentence ___________________________________________________