CCSS.Math.Content.2.MD.A
The standard
Measure and estimate lengths in standard units.
Common Core State Standards for Mathematics
What this standard means
Students need to use rulers, yardsticks, meter sticks, and measuring tapes to measure length. They should choose a sensible tool and unit, line up the zero mark, and record the number with the unit. They also need to make reasonable estimates before measuring.
Mastery looks like measuring objects accurately, comparing measurements, and explaining why an estimate makes sense. Common trouble spots are starting at the edge of the ruler instead of zero, mixing inches and centimeters, choosing a poor tool, and writing a number without a unit.
Ways to teach it
- Have pairs measure five classroom objects with rulers, then remeasure one object using a different tool and compare results.
- Ask students to write: How did your estimate help you decide if your measurement made sense?
- Show a pencil, book, and desk, and have students estimate, measure, and label each length with the correct unit.
- Measure the length of shoelaces, lunch boxes, or playground items, then discuss which tool worked best for each object.
Plan a lesson for CCSS.Math.Content.2.MD.A
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Related standards
- CCSS.Math.Content.2.MD.A.2
Measure the length of an object twice, using length units of different lengths for the two measurements; describe how the two measurements relate to the size of...
- CCSS.Math.Content.2.MD.A.3
Estimate lengths using units of inches, feet, centimeters, and meters.
- CCSS.Math.Content.1.MD.A
Measure lengths indirectly and by iterating length units.
- CCSS.Math.Content.2.MD.A.1
Measure the length of an object by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes.