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Private: Learning Math: Measurement
Classroom Case Studies, K-2 Part B: Reasoning About Measurement (40 minutes)
Session 10: K-2, Part B
In This Part
- Exploring Standards
- Analyzing a Case Study
Exploring Standards
The National Council of Teachers of Mathematics (NCTM, 2000) has identified measurement as a strand in its Principles and Standards for School Mathematics. In grades pre-K-12, instructional programs should enable all students to do the following:
- Understand measurable attributes of objects and the units, systems, and processes of measurement
- Apply appropriate techniques, tools, and formulas to determine measurements
Recognize the attributes of length, volume, weight, area, and time•Compare and order objects according to these attributesIn pre-K-2 classrooms, students are expected to do the following:
- Understand how to measure using nonstandard and standard units•Select an appropriate unit and tool for the attribute being measured
- Measure with multiple copies of units of the same size, such as paper clips laid end to end
- Use repetition of a single unit to measure something larger than the unit; for instance, measuring the length of a room with a single meterstick
- Use tools to measure
- Develop common referents for measures to make comparisons and estimates
The NCTM (2000) Measurement Standards suggest that students will begin to understand attributes of area by “looking at, touching, or directly comparing objects.” Instruction that provides students with opportunities to measure and explain their findings will help teachers further this goal. Furthermore, “although for many measurement tasks students will use nonstandard units, it is appropriate for them to experiment with and use standard measures such as centimeters and meters and inches and feet by the end of grade 2” (NCTM, 2000, p. 105).
Principles and Standards for School Mathematics © 2000 by the National Council of Teachers of Mathematics, Inc. www.nctm.org. All rights reserved. This material may not be copied or redistributed electronically or in other formats without written permission from NCTM. standards.nctm.org
Standards are listed with the permission of the National Council of Teachers of Mathematics (NCTM). NCTM does not endorse the content or validity of these alignments.
Analyzing a Case Study
To begin the exploration of what measurement topics look like in a classroom at your grade level, you will watch a video segment of a teacher who took the Measurement course and then adapted the mathematics to her own teaching situation. We will begin by looking at some of the content addressed in the videotaped lesson. Note 2
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Video Segment Watch this video segment from Ms. Guerino’s class and think about how both the lesson and the teacher are assisting students in making sense of some of the measurement concepts described in Part A. You can find this segment on the session video approximately 11 minutes and 42 seconds after the Annenberg Media logo. |
Problem B1
Prior to this lesson, students worked with nonstandard units to measure area. What might students learn from measuring objects using units like circular discs and paper clips?
Problem B2
Before her students determine which rectangle has a larger area, Ms. Guerino asks them to predict which one is larger. Where in the lesson are students using estimating techniques to decide which rectangle is larger? Why is it important to have students make estimates before they actually begin measuring?
Problem B3
Why do you think Ms. Guerino asked students to measure the two shapes using both square inches and square centimeters? How might discussion among students and the teacher contribute to students’ understanding of conservation of area? What other measurement concept was Ms. Guerino exploring when she asked students to cover the shapes with different-sized units?
Problem B4
Is it important to have misconceptions surface in a lesson? If misconceptions do occur, how can they be addressed?
Notes
Note 2
The purpose of the video segments is not to reflect on the teaching style of the teacher portrayed. Instead, look closely at the methods the teacher uses to bring out the ideas of measurement while engaging her students in activities.
Solutions
Problem B1
Measuring with nonstandard units provides students the opportunity to choose the unit they want and to gain a sense of the physical process of a measuring experience. When students use nonstandard units (e.g., paper clips, playing cards, or buttons) to measure area, they notice that they can’t cover the surface completely. The other difficulty with using nonstandard measures is that students can’t compare the measures; for example, 110 paper clips vs. 12 playing cards.
Problem B2
Students made predictions about whether the rectangle or square was larger at the start of the lesson. Doing so helps them consider which attributes are important as well as visualize how much space the shapes take up. Students may even visualize cutting up one shape to cover the other. In the video, one group of students compares the dimensions of the two shapes. The students in this group notice that the length of the rectangle is longer than that of the square, and then they use finger span to estimate that the heights of both the rectangle and square are the same. They conclude that the rectangle must be larger.
Problem B3
Ms. Guerino asked students to use both square inches and square centimeters to measure the shapes so that she could address the idea of conservation. Students may not realize that the areas will stay the same even if they measure with different-sized units.
To help students understand conservation, ask them to predict which rectangle will have the largest area before they cover the shapes with the new unit. Also, asking students to explain why the larger shape is still larger, and if it will always be larger, can help them reason about conservation.
Another measurement concept that Ms. Guerino explored when she asked students to cover the shapes with different-sized units is the concept that the smaller the unit, the greater the number needed to cover the shapes.
Problem B4
It is not only important, but actually helpful when misconceptions surface in a lesson. Misconceptions often provide the contrast needed for students to understand an idea. One strategy to use when misconceptions arise is to present two opposing viewpoints and ask students which idea they agree with and why. You can also ask students to give a counterexample, or give the students a counterexample yourself and ask them what they think. Another reason why it is important to discuss misconceptions: By confronting a conception that turns out to be incorrect, students become engaged in understanding why it is a misconception.
