Lesson 2

In Twos, Threes, and More

Est. Class Sessions: 3

Daily Practice and Problems

Teacher Notes
X

TIMS Task

Pressing 10 + 10 = = = on a calculator with a constant function will cause the calculator to count by 10s.

To count backward from 500 on a calculator, press 500 − 10 = = = =.

Counting by tens forward and backward will help students use counting strategies when adding and subtracting multiples of 10.

Counting by 10s to or from 500 takes about 30 seconds.

D. Calculator Counting with 10s

Work with a partner to find how long it will take to count to 500. One partner will count. The other will time how long the counting takes.

  1. Predict how long it will take to count by 10s to 500. Use a calculator to count by 10s to 500. How long did it take?
  2. Predict how long it will take to count backward by 10s from 500 to 0. Use a calculator to help you count. Was your prediction close? Explain why or why not.