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Learning Math: Measurement

The Metric System

Learn about the relationships between units in the metric system and how to represent quantities using different units. Estimate and measure quantities of length, mass, and capacity, and solve measurement problems.

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In This Session

Part A: Metric System Basics
Part B: Metric Units

There are two measurement systems used in the United States: the English or U.S. customary system and the metric system. A measurement system consists of units, which are defined in specific ways, and their symbols. Within a system, there are relationships between units, such as between inches and feet in the English system or centimeters and meters in the metric system. In a coherent measuring system, a small number of independent units fit together in simple ways, and all other units are defined in terms of the base units. The metric system is almost completely coherent, whereas the English system is not coherent at all! In this session, you will learn about the metric system. Note 1

For the list of materials that are required and/or optional in this session,
see Note 2.


Learning Objectives

In this session, you will learn to do the following:

  • Understand the relationships between units within the metric system
  • Represent quantities using different units
  • Estimate and measure quantities of length, mass, and capacity, and solve measurement problems
  • Understand the basic measurement ideas that lead to accurate measurement

Key Terms

New In This Session

Metric System: The metric system is a system of measurement based on standard prefixes and powers of 10. It has base units for length, capacity, mass, etc., and is more consistent than other systems of measurement.

Prefixes: The prefixes used by the metric system indicate the powers of 10 used to convert from one unit type to another. Common prefixes include “kilo-” for 1,000, “centi-” for one 100th, and “milli-” for one 1,000th.

Referents: Referents make measurement tasks easier by establishing benchmarks for a certain measure. Two examples of referents are a stretch of road that is about a mile and an adult arm length that is about a meter.

U.S. Customary System: The U.S. customary system is the system of measurement typically used in the United States. Its units include inches, gallons, and pounds. This system is not as consistent as the metric system. Additionally, conversions between units are nonstandard — how many people know how many drams are in a pennyweight?!


Note 1

Most Americans are not very comfortable using the metric system. We can’t estimate with any accuracy the length of a room in meters, or approximate a kilogram of potatoes. Yet we live in a world that is metric; the United States is one of the few nations that has not converted to the exclusive use of the metric system.

This session introduces the key features of the metric system. We examine the relationships between units within the metric system and learn how to represent quantities using different units. You will have an opportunity to develop metric benchmarks by estimating and measuring quantities of length, mass, and capacity.

Remember, children who frequently use materials based on the metric system (for example, metersticks and centimeter cubes) will be able to visualize meters, centimeters, grams, and so on and the relationships between certain units.


Note 2

Materials Needed:

  •  Chalk
  • Empty plastic 1 L, 2 L, and 3 L bottles

Additional materials needed:

  •  Metric tape measure and ruler
  • 12 metersticks
  • Metric trundle wheels (optional)
  • A variety of metric scales: two-pan balance scale, spring scale, and a personal scale (optional)
  • Metric graduated beakers (500 mL or 1,000 mL)
  • Metric weights (1 g, 5 g, 10 g, 25 g, 100 g, 500 g, 1 kg) (you could also use centimeter snap-together cubes that weigh 1 g each) (optional)

The above materials can be purchased from:

500 Greenview Court
Vernon Hills, IL 60061
Phone: 800-445-5985/800-816-5050 (Customer service)
Fax: 800-875-9643/847-816-5066

Series Directory

Learning Math: Measurement


Produced by WGBH Educational Foundation. 2002.
  • Closed Captioning
  • ISBN: 1-57680-728-2