Math Background

Lesson: Comparing Lengths, Weights, and Capacities
Developing the Concept

When children are comfortable comparing objects using linear measurement, they will be ready to explore capacity and weight.

Materials: book, classroom objects, balance scale, cup, rice, containers, chart paper, and markers

Preparation: Explain that children are going to play a game called “More or Less.“ Begin by passing around the book and letting each child lift it to get a sense of its weight.

  • Ask: I'm going to choose another object. How can I tell if it weighs more or less than the book?
    Children may say they can hold each object and compare them or use a balance scale. Try each suggestion, demonstrating how to use the balance scale. Then have children choose three objects to compare. Have them record the results of their comparisons on a chart such as the one shown below.
    More or less chart: More than a book - Less than a book. More than a backpack - less than a backpack. More than a pencil - less than a pencil.
  • Ask: How can I put these objects in order from heaviest to lightest?
    Children may suggest comparing pairs of objects to determine the order. Try their suggestions.

    Then display the measuring cup and identify it. Choose a container and continue to play “More or Less,” this time comparing capacities.
  • Ask: How can I find out if the (glass) holds more or less than the cup?
    Children may suggest filling the cup and then pouring the rice into the (glass). Try their suggestions.

    Then have children choose three containers. Continue with other containers and use a picture/word list to record the results.
    More or less chart: More than a cup - Less than a cup. More than a pitcher - less than a pitcher. More than a spoon - less than a spoon.
  • Ask: How could I put these containers in order from the one that holds the least to the one that holds the most?
    Children may suggest comparing pairs of containers to determine the order. Encourage them to experiment with their ideas.

Wrap-Up and Assessment Hints
Provide many opportunities for children to compare the lengths, capacities, and weights of objects using different units, and continue to look for measurement opportunities in your classroom to reinforce these concepts. Art and science activities also provide excellent opportunities to incorporate these concepts.

Houghton Mifflin Math Grade K