Compare Decimals on the Number Line

10 min

Narrative

The purpose of this Notice and Wonder is for students to look at different number lines that all start at 0 but show different decimals. The number lines are nested, that is each successive one is contained in the previous one. The key points for students to notice are that the number lines all have decimals on them and that the size of those decimals is getting smaller. In the lesson, they will plot decimals on number lines like these.

Launch

  • Groups of 2
  • Display the image.
  • “What do you notice? What do you wonder?”
  • 1 minute: quiet think time
Teacher Instructions
  • “Discuss your thinking with your partner.”
  • 1 minute: partner discussion
  • Share and record responses.

Student Task

What do you notice? What do you wonder?

number lines
3 number lines. Top number line, scale 0 to 1 by tenths. Middle number line, scale from 0 to 1 tenths by hundredths. Bottom number line, scale 0 to 1 hundredth by thousands. Arrays going from the 0 on the top number line to the zeroes on the middle number line and third number line. 1 arrow going from the second tick mark on the top number line to the last tick mark on the middle number line labeled 1 tenth. One arrow going from the second tick mark on the middle number line to the last tick mark on the bottom number line labeled 1 hundredth.

Sample Response

Students may notice:

  • There are three number lines.
  • Each number line looks like it comes out of the one above it.
  • Each number line has smaller numbers on it.

Students may wonder:

  • Are we going to use these number lines?
  • Can I keep going, putting in more number lines?
  • What numbers go on the tick marks?
Activity Synthesis (Teacher Notes)
  • “What are the tick marks on the top number line?” (one tenth, two tenths, three tenths, and so on)
  • “Today we are going to use number lines like these to locate different decimals.”
Standards
Addressing
  • 5.NBT.3.b·Compare two decimals to thousandths based on meanings of the digits in each place, using >, =, and < symbols to record the results of comparisons.
  • 5.NBT.A.3.b·Compare two decimals to thousandths based on meanings of the digits in each place, using <span class="math">\(&gt;\)</span>, =, and <span class="math">\(&lt;\)</span> symbols to record the results of comparisons.

15 min

10 min

10 min