Lesson 4

Measuring Mass

Est. Class Sessions: 2–3
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Mathematical Standards

3.OA.A
Represent and solve problems involving multiplication and division. (3.OA.A.3)
3.OA.B
Understand properties of multiplication and the relationship between multiplication and division. (3.OA.B.5)
3.OA.D
Solve problems involving the four operations, and identify and explain patterns in arithmetic. (3.OA.D.9)
3.MD.A
Solve problems involving measurement and estimation. (3.MD.A.2)

Standards for Mathematical Practice

MP1.
Make sense of problems and persevere in solving them.
MP2.
Reason quantitatively.
MP3.
Construct viable arguments and critique the reasoning of others.
MP4.
Model with mathematics.
MP5.
Use appropriate tools strategically.
MP6.
Attend to precision.

In Parts 1 and 2, students find the mass of small objects using a two-pan balance and standard masses. They discuss why they may get different answers for the mass of the same objects and whether these differences are reasonable. In Part 3 students use two-pan balances to write number sentences using the greater than, less than, and equal signs.

Content in this Lesson

  • Measuring mass in grams [E6].
  • Dealing with precision and accuracy.
  • Solving problems involving the measurement of mass [E3].
  • Writing number sentences to represent comparisons using the less than (<), greater than (>), or equal sign [E2].
  • Collecting and organizing data in a table [E7].
  • Identifying multiplicative patterns represented in a table [E1].
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Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Guide
Student Activity Book

Teacher Resources

 Teacher Guide - digital

Supplies for Students

one small object from home to mass

Supplies for Student Groups

two-pan balance
set of standard masses (ten 1-gram, ten 5-gram, five 10-gram, and two 20-gram masses)
small piece of clay (for leveling the balance)
set of objects to measure. See Materials Preparation.

Materials for the Teacher

Display of Compare to 20 Grams Master (Teacher Guide)
Unit 12 Assessment Record
sandwich, calculator, pillow, brick for demonstration, optional
chart paper

Materials Preparation

Gather Objects to Mass. For this activity you will need to gather at least four everyday objects for each group to weigh. The mass of the objects should be limited to about 150 g or less, and they should be small enough to fit in your balance pan. Try to include some large, light items and some small, heavy ones. Figure 1 shows the mass of some common objects.

Figure 1
Figure 1: Mass of common objects

One item in each set must be identical among the groups since they will be comparing their findings for one of the objects. Because most classrooms have a set of calculators that are all the same model, a calculator is a good choice. Here are some other objects teachers have used:

  • new pencils
  • empty milk cartons
  • whole pieces of chalk
  • pattern blocks
  • new erasers

Assessment in this Lesson

Assessment Expectation Assessed

Observe
Measuring Mass
Check-In: Question 3
Student Guide
Page 350
and corresponding Feedback Box
Teacher Guide - digital
E6.
Measure mass in grams.
E7.
Collect and organize data in a table.

Balancing Masses
Student Activity Book
Pages 490–491
E2.
Write number sentences to represent comparisons using the less than (<), greater than (>), or equal sign.
E3.
Solve multiplication and division problems involving measurement (e.g., mass and length).