2.9.A
The Standard
find the length of objects using concrete models for standard units of length
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students measure an object's length by placing same-sized standard units along one edge. They line up the units without gaps or overlaps, then count and name them.
What Mastery Looks Like
- Students place equal-sized units end to end from one endpoint to the other, with no gaps or overlaps. They count the units and name the correct unit.
Common Misconceptions
- Students may leave gaps, overlap units, or begin measuring past the object's endpoint. They may count marks instead of spaces or mix centimeters and inches.
How to Assess It
- Give each student a pencil and centimeter cubes. Ask, “How long is the pencil, and how did you place the cubes to measure it?”
Lesson moves
Ways to Teach It
Have pairs measure classroom objects by lining up centimeter cubes or inch tiles, then record each object and its length.
Ask students to explain why a row of cubes with gaps gives an incorrect measurement, using a labeled drawing.
Play Measurement Match by having students pair object cards with cube-strip models showing the same length.
Measure a lunchbox, book, and desk item with inch tiles, then decide which object needs the most material to cover one edge.
Keep exploring
Related Standards
- 1.7.A
use measuring tools to measure the length of objects to reinforce the continuous nature of linear measurement;
- 1.7.B
illustrate that the length of an object is the number of same-size units of length that, when laid end-to-end with no gaps or overlaps, reach from one end of th...
- 2.9.D
determine the length of an object to the nearest marked unit using rulers, yardsticks, meter sticks, or measuring tapes
- 2.9.E
determine a solution to a problem involving length, including estimating lengths
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