Math Background

Lesson: Measurement
Developing the Concept

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In this lesson, the students will work with Customary and Metric units of weight, capacity and temperature.

Materials: balance, 16 1-oz weights, 1-lb weight, a 1-cup measure, a 1-pt container, a 1-qt container, a 1-gal container, a 1-L container, a dropper, water, 1-lb object (box of raisins, rice, brown sugar, or soup can), picture of an American bison; and a copy of Worksheet A (PDF file) and the Weights and Measures (PDF file) worksheet.

Prerequisite Skills and Concepts: Students should be familiar with both customary and metric units of weight/mass, and capacity.

  • Say: Today we will be working with customary and metric units of capacity, weight or mass, and temperature. We will start by reviewing customary units of capacity.
  • Ask: What is capacity? (how much a container can hold) What are the customary units of capacity?
    Elicit the responses cups, pints, quarts and gallons. Name any units that the students do not mention. Write the units on the chalkboard in order from least capacity to greatest capacity.
  • Ask: I want to find the number of cups in a pint. How can I do that?
    Students should say that you can pour cups of water into a pint to see how many cups it takes. Demonstrate this for the students.
  • Ask: How many cups equal 1 pint? (2 c)
  • Say: Now I want to find the number of pints in a quart. Use the pint container to empty 2 pints of water into a quart container.
  • Ask: How many pints equal 1 quart? (2 pt)
  • Say: Now let's find the number of quarts in a gallon.
    Demonstrate for the students.
  • Ask: How many quarts equal 1 gallon? (4 qt)
  • Ask: What if I wanted to find the number of pints in 3 gallons? Is there an easier way to do this than to actually pour pints into gallons?
    Elicit the fact that there are 2 pints in a quart and 4 quarts in a gallon, so there are 8 pints in 1 gallon, and 24 pints (8 x 3) in 3 gallons.
  • Say: Since there are 8 pints in a gallon, 3 x 8 is the number of pints in 3 gallons. So 24 pints equals 3 gallons. We multiplied because we were converting from a larger unit, gallons, to a smaller unit, pints. If we were converting from pints to gallons, we would have divided. Now let's take a look at metric units of capacity.
  • Ask: What are some metric units of capacity?
    Students should say milliliter and liter. Hold up a 1-liter container and a dropper with 1 milliliter of water in it.
  • Say: You know that all units in the metric system are related by factors of ten. That means that a liter (hold up the 1-liter bottle) is either 10, 100, or 1,000 times the size of a milliliter. (Hold up the dropper.)
  • Ask: How many times larger than a milliliter is a liter? (1,000) How do you know?
    Students may say that they can tell by comparing the amount in the dropper with the amount in the 1-liter bottle, or that the prefix milli- means 1,000. If they do not mention the prefix, remind them of this relationship.
  • Say: Now let's look at weight. What are the customary units of weight? (ounces and pounds)
  • Ask: If I place a 1-pound weight on the balance, how many 1-ounce weights would it take to balance the scale?(16)
    Demonstrate this for the students.
  • Ask: 16 ounces equal one pound. So, how many ounces are in 5 pounds?
    Students may say 80 ounces. Elicit how they got 80 and that they multiplied because they were converting from a larger unit to a smaller unit.
  • Say: There is another customary unit of measure called a ton. A ton equals 2,000 pounds. An American bison weighs about a ton. This (hold up a 1-pound object) weighs about 1 pound. It would take 2,000 of these to equal a 1-ton bison.
  • Ask: Now let's talk about metric units of mass. What metric units of mass do you know?
    Students may say grams and kilograms.
  • Ask: Which is larger—a gram or a kilogram? (kilogram) How do you know?
    Elicit that gram is the base unit and that the prefix kilo- means that it is 1,000 times greater than a gram.
  • Say: A baseball bat weighs about a kilogram.
  • Ask: How could you find the number of grams in 12 kilograms?
    Elicit that you would multiply the number of kilograms, 12, by the number of grams in one kilogram, 1,000, to find that 12 kilograms = 12,000 grams.
  • Say: The last units we will look at are units for measuring temperature. Let's compare temperatures measured in degrees Fahrenheit, which is the customary unit, to temperatures measured in degrees Celsius, which is the metric unit. Look at the worksheet. Let's fill in some common temperatures to use as reference points. On your Fahrenheit scale, write “water freezes” next to 32°. Now write “water freezes” next to 0° on your Celsius scale.
  • Ask: What Fahrenheit temperature would be an example of a hot summer day?
    Accept reasonable answers and have students label one temperature “hot summer day.”
  • Say: On the Fahrenheit scale, the freezing point of water is 32°. But 32° Celsius is quite hot. Label 32° “hot summer day.”
  • Ask: What would be a very cold temperature in degrees Fahrenheit? In degrees Celsius? (Answers will vary. Accept answers below 32°F and 0°C.)
  • Ask: Look at the numbers below zero on either thermometer. What symbol is to the left of these numbers? (a negative sign)
  • Say: Numbers that are less than zero are called negative numbers. Now let's learn how to find differences between temperatures on the Fahrenheit scale. Let's pretend it is winter. The high temperature for the day was 17°F. The low temperature was −12°F. Let's find the difference between the high and low temperatures. We are going to count down from 17°F to −12°F to find the difference.

    Demonstrate finding the difference by counting down 7 degrees, then counting down by tens until you read −10°F. Finally count down 2 more degrees to −12°F. Repeat the activity with the Celsius thermometer.

Wrap-Up and Assessment Hints
Use the Weights and Measures (PDF file) worksheet to assess students' understanding of metric and customary units of weight and capacity. Answers are annotated on the teacher version (PDF file) of the worksheet.

Give students a copy of the weather page from a local newspaper or find a copy of an Internet weather page with both Fahrenheit and Celsius temperatures. Have them use their "thermometers" to find the difference between high and low daily temperatures. Using international temperatures will provide a wider array of numbers and help students gain practice with negative temperatures.

Houghton Mifflin Math Grade 4