Round to the Nearest Ten and the Nearest Hundred

10 min

Narrative

The purpose of this Choral Count is for students to practice counting by 10 and by 100 and to notice patterns in the count. These understandings help students develop fluency, see that multiples of 100 are also multiples of 10, and prepare them to round large numbers to the nearest ten and the nearest hundred.

Launch

  • “Count by 10, starting at 0.”
  • Record as students count.
  • Stop counting and recording at 200.
  • “Count by 100, starting at 0.”
  • Record as students count.
  • Stop counting and recording at 900.
Teacher Instructions
  • “What patterns do you see?”
  • 1–2 minutes: quiet think time
  • Record responses.
Solution Steps (4)
  1. 1
    Count by 10 starting at 0
    →0, 10, 20, 30, ... up to 200
  2. 2
    Count by 100 starting at 0
    →0, 100, 200, 300, ... up to 900
  3. 3
    Notice patterns in the counts
    →Tens place increases by 1 when counting by 10; hundreds place increases by 1 when counting by 100
  4. 4
    Recognize 100 and 200 appear in both counts
    →100 = 10 tens; multiples of 100 are also multiples of 10

Sample Response

  • Record the first count vertically, with 10–100 in one column and 110–200 in the second column.
  • Record the second count vertically in one column, from 100–900.
Sample responses:
  • The tens place goes up by 1 as you move down a row in the first count.
  • The hundreds place goes up by 1 as you move down a row in the second count.
  • There are no ones in any of the numbers in the first count.
  • The first count is all multiples or groups of 10.
  • There are no tens or ones in any of the numbers in the second count.
  • The second count is all multiples or groups of 100.
Activity Synthesis (Teacher Notes)
  • “Why do 100 and 200 show up in both of these counts?” (We say 100 and 200 when we're counting by tens or hundreds. We can think of 100 as 10 tens and 200 as 20 tens. 100 and 200 are multiples of 10 and multiples of 100.)
Standards
Building On
  • 2.NBT.2·Count within 1000; skip-count by 2s, 5s, 10s, and 100s.
  • 2.NBT.A.2·Count within 1000; skip-count by 5s, 10s, and 100s.
Building Toward
  • 3.NBT.1·Use place value understanding to round whole numbers to the nearest 10 or 100.
  • 3.NBT.A.1·Use place value understanding to round whole numbers to the nearest 10 or 100.

20 min

15 min