Decimals on Number Lines

10 min

Narrative

This Warm-up prompts students to carefully analyze and compare different representations of numbers. In making comparisons, they solidify their understanding of the connections across representations and have a reason to use language precisely (MP6). The activity also enables the teacher to hear the terminologies students know and how they talk about characteristics of the representations.

Launch

  • Groups of 2
  • Display the image.
  • “Pick 3 that go together. Be ready to share why they go together.”
  • 1 minute: quiet think time
Teacher Instructions
  • “Discuss your thinking with your partner.”
  • 2–3 minutes: partner discussion
  • Share and record responses.

Student Task

Which 3 go together?

A
Written description. Eight tenths.

B
Fraction. Numerator, eighty. Denominator, ten.

C
Decimal. Eighty hundredths.

D
Number line. First tick mark, 0. Second tick mark, 1 tenth. Point A located at the ninth tick mark.

Sample Response

Sample Responses:

  • A, B, and C go together because they have 8.
  • A, B, and D go together because they have tenths.
  • A, C, and D go together because they are equivalent to 810\frac{8}{10}.
  • B, C, and D go together because they are expressed in numerals instead of words.
Activity Synthesis (Teacher Notes)
  • “How might we revise one or more of the options so that they all represent the same value?” (Sample responses:
    • Change the 8010\frac{80}{10} to 810\frac{8}{10} or 80100\frac{80}{100}.
    • Change Option A to say “eight,” Option C to say “8” or “8.0,” and the label for the first tick mark in Option D to say “1.”)
Standards
Addressing
  • 4.NF.C·Understand decimal notation for fractions, and compare decimal fractions.
  • 4.NF.C·Understand decimal notation for fractions, and compare decimal fractions.

20 min

15 min