Length Measurements

10 min

Narrative

This Warm-up prompts students to carefully analyze and compare length measurements given in different units, reminding about the relationships between yards, feet, and inches. In making comparisons, students need to attend to both the meaning of each unit and its relationships to other units, and they have a reason to use language precisely (MP6). The activity also enables the teacher to hear the terminology students use to talk about the characteristics of length measurements given in different units.

Launch

  • Groups of 2
  • Display the four measurements.
  • “Pick 3 measurements 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

3 feet

B

(3×1)(3\times1) yards

C

(2×18)(2\times18) inches

D

(13+13+13)(\frac{1}{3} + \frac{1}{3} + \frac{1}{3}) yard

Sample Response

Sample responses:

A, B, and C go together because:

  • The units are in plural form.
  • They have whole numbers.

A, B, and D go together because:

  • They have the number 3.

A, C, and D go together because:

  • Their value is equivalent to 1 yard.

B, C, and D go together because:

  • They have operations.

Synthesis

  • “All four quantities are lengths. What do you notice about these lengths?” (They are in different units. Three of them are equivalent to 1 yard, and one of them is 3 yards.)
  • “If we convert into feet the quantities equivalent to 1 yard, what measurement will they all be?” (3 feet.)
  • “What if we convert them into inches?” (36 inches.)
Standards
Building On
  • 4.MD.1·Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two column table. <em>For example, know that 1 ft is 12 times as long as 1 in. Express the length of a 4 ft snake as 48 in. Generate a conversion table for feet and inches listing the number pairs (1, 12), (2, 24), (3, 36), …</em>
  • 4.MD.A.1·Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table. <span>For example, know that 1 ft is 12 times as long as 1 in. Express the length of a 4 ft snake as 48 in. Generate a conversion table for feet and inches listing the number pairs <span class="math">\((1, 12)\)</span>, <span class="math">\((2, 24)\)</span>, <span class="math">\((3, 36)\)</span>, …</span>

15 min

20 min