Anchoring Units of Measurement
10 min
Teacher Prep
Setup
Narrative
This Warm-up prompts students to recall units of volume and reason about appropriate units of measurement in order to make an estimate. It gives the teacher an opportunity to hear what students know about measurement units for volume and how they choose a unit.
Launch
Arrange students in groups of 2. Tell students that they will be estimating the volume of a tiny salt shaker. Ask students to give a signal when they have an estimate. Give students 1 minute of quiet think time followed by 2 minutes to discuss their estimates with a partner. Ask them to discuss the following questions, displayed for all to see:
- “How close are your estimates to one another?”
- “How did you decide on the unit of measure?”
- “Which parts of the image were important for making your estimate?”
- “Could you record your measurement using a different unit?”
Student Task
Estimate the volume of the tiny salt shaker.
Sample Response
Reasonable estimates would be close to 3 teaspoons, 15 milliliters, or 15 cubic centimeters.
Activity Synthesis (Teacher Notes)
Poll the class on their estimates. Record and display the estimates for all to see. Invite a few students to share how they chose their unit of measurement and any information in the image that informs their estimates. After each explanation, solicit questions from the class that could help students clarify their reasoning. If only one or two units are used in the estimates, ask if there are other units that could be used.
If time permits, tell students that the length, width, and height of the shaker are each 2.5 centimeters. Ask them to use that information to check the reasonableness of their estimates. It may help to know that 1 cubic centimeter is the same volume as 1 milliliter.
During the discussion, students may question if the volume of the shaker as determined by the exterior side lengths indicates how much salt the shaker can hold. Welcome questions such as these and discuss how students’ assumptions affected their estimates.
Standards
- 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>
20 min
Knowledge Components
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Anchoring Units of Measurement
10 min
Teacher Prep
Setup
Narrative
This Warm-up prompts students to recall units of volume and reason about appropriate units of measurement in order to make an estimate. It gives the teacher an opportunity to hear what students know about measurement units for volume and how they choose a unit.
Launch
Arrange students in groups of 2. Tell students that they will be estimating the volume of a tiny salt shaker. Ask students to give a signal when they have an estimate. Give students 1 minute of quiet think time followed by 2 minutes to discuss their estimates with a partner. Ask them to discuss the following questions, displayed for all to see:
- “How close are your estimates to one another?”
- “How did you decide on the unit of measure?”
- “Which parts of the image were important for making your estimate?”
- “Could you record your measurement using a different unit?”
Student Task
Estimate the volume of the tiny salt shaker.
Sample Response
Reasonable estimates would be close to 3 teaspoons, 15 milliliters, or 15 cubic centimeters.
Activity Synthesis (Teacher Notes)
Poll the class on their estimates. Record and display the estimates for all to see. Invite a few students to share how they chose their unit of measurement and any information in the image that informs their estimates. After each explanation, solicit questions from the class that could help students clarify their reasoning. If only one or two units are used in the estimates, ask if there are other units that could be used.
If time permits, tell students that the length, width, and height of the shaker are each 2.5 centimeters. Ask them to use that information to check the reasonableness of their estimates. It may help to know that 1 cubic centimeter is the same volume as 1 milliliter.
During the discussion, students may question if the volume of the shaker as determined by the exterior side lengths indicates how much salt the shaker can hold. Welcome questions such as these and discuss how students’ assumptions affected their estimates.
Standards
- 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>