Math Background

Lesson: Measuring Weight, Mass, and Capacity
Introducing the Concept

Developing children's understanding of measurement is an ongoing task. Children are becoming familiar with the units that are used to measure different things. In this lesson they will learn how to compare items by weight in pounds and by mass in kilograms.

Materials: balance, 1-pound weight, 1-kilogram mass

Preparation: Gather items that weigh approximately one-half pound, 1 one-half pounds, and 3 pounds.

Prerequisite Skills and Background: Children should understand the concepts “more than“ and “less than.“ They should also know the vocabulary terms pound and kilogram.

  • Say: Today we will compare objects and decide if they weigh more or less than a pound. This is a 1-pound weight.
    Pass the weight around the class and have children feel how heavy it is. Then hold up an object that weighs about 1 one-half pounds.
  • Ask: Does this object weigh more or less than one pound?
    Elicit opinions from children.
  • Ask: How can we tell if this object weighs more or less than a pound?
    Children may suggest that they could hold it and compare its weight to the 1-pound weight, or they could use the balance to weigh it. Pass the object around the class and have children feel its weight. Then put the 1-pound weight on one side of the balance and the 1 one-half pound object on the other.
  • Ask: Now who can tell if this object weighs more or less than a pound?
    Children should say that it weighs more than a pound, because the balance shows that the object is heavier than the 1-pound weight.

    Repeat this activity, using the objects that weigh more than one pound.

  • Say: Now let's see if we can find an object that weighs less than a pound.
    Have a volunteer choose an object that he or she thinks weighs less than 1 pound. Pass the object around the class and have children feel how heavy it is. Have them tell if they agree with the volunteer. Then weigh the object.
  • Ask: How can we tell if this object weighs more or less than a pound?
    Discuss how the balance indicates the answer.
  • Ask: If the object were exactly 1 pound, how would the balance show it?
    (The balance would show that both sides of the scale “balance,” or hold the same weight.)

    Repeat the activity until you feel that children understand measuring weight in pounds.

    You can use this same activity to estimate and measure objects that are a kilogram or are greater than or less than a kilogram.


Houghton Mifflin Math Grade 2