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Measuring Blocks


Alignments to Content Standards: 1.MD.A.2 1.OA.A.1

Task

Materials

  • Unifix cubes
  • Large blocks in different sizes or varying lengths of sentence strips

Note: The large blocks or the cut-up lengths of sentence srtips need to measure a whole number of unifix cubes whose combined length is less than or equal to 20 unifix cubes.

Actions

  • Have students work in pairs. Give each pair two blocks or strips to measure using unifix cubes. After they have measured their block, say,
Ask your partner how many unifix cubes long their block/paper strip is. How long will the two different blocks be together if they are laid end-to-end? First try to figure this out. Then put the blocks end-to-end and measure it to check your answer.
  • Ask students to explain how they solved the problem and whether their answer checked out correctly. Even if students added correctly, they may not have lined up the unifix cubes very carefully and could get different lengths. This is a good opportunity to talk about how important it is to be careful when measuring. The teacher may also need to ensure that all students are "clicking" their unifix cubes together so that there aren't gaps between the unifix cubes which would alter the measurements.

  • Finally, ask the students to write equations to represent their work.

For students who are ready for a more complex question ask,

Imagine you put another block end-to-end with the first one you measured. Together, they measure [X number] of unifix cubes. How long is the new block? Draw a picture to explain how you know.

IM Commentary

This task provides a measuring experience that goes beyond simply measuring and recording the length of classroom items, and should be taught after student are already competent with measuring and recording lengths, as well as addition to 20. (See 1.MD How Long? for practice with this skill). In this task, student get to combine two skills, measuring and addition, and are asked to relate these two ideas together. The goal should be for students to understand that you add the lengths of individual objects to get the length of the two objects laid end-to-end.

In second grade, students take this idea much farther, see 2.MD.B, Relate addition and subtraction to length.