Lesson 3

Balanced and Equal

Est. Class Sessions: 1–2
X

Mathematical Standards

2.NBT.A
Understand place value. (2.NBT.A.2, 2.NBT.A.4)
2.NBT.B
Use place value understanding and properties of operations to add and subtract. (2.NBT.B.5, 2.NBT.B.7)

Standards for Mathematical Practice

MP2.
Reason quantitatively.
MP3.
Construct viable arguments and critique the reasoning of others.
MP5.
Use appropriate tools strategically.
MP7.
Look for and make use of structure.
MP8.
Look for and express regularity in repeated reasoning.

Students use two-pan balances and 1-, 5-, 10-, 20-, 50-, and 100-gram masses to practice composing and decomposing numbers. Through this process, they recognize that different partitions of a number have the same total because the pans balance. Students then apply the commutative and associative properties of addition to write number sentences that represent mass.

Content in this Lesson

  • Composing and decomposing numbers using ones, fives, tens, twenties, fifties, and hundreds [E1].
  • Using the equal sign to show comparisons of quantities [E2].
  • Recognizing that different partitions of a number have the same total [E4].
  • Applying the commutative and associative properties of addition to write number sentences that represent mass [E5].

Daily Practice and Problems G–H

G. Using 10

H. Sharing Stickers

X

Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Activity Book

Teacher Resources

 Teacher Guide - digital

Supplies for Student Pairs

two-pan balance (zeroed in Lesson 1)
standard gram mass set (one 100-g, two 50-g, ten 20-g, ten 10-g, fifteen 5-g, twenty 1-g masses)

Materials for the Teacher

Display of Natasha’s Gram Masses Master (Teacher Guide)
Unit 8 Assessment Record
Math Facts Class Record
two-pan balance (zeroed in Lesson 1)
standard mass set (one 100-g, two 50-g, ten 20-g, ten 10-g, fifteen 5-g, twenty 1-g masses)
small container for standard mass set

Materials Preparation

Prepare Two-Pan Balances and Mass Sets. Assemble the two-pan balances, if necessary, and gather standard mass sets for each student pair.

Assessment in this Lesson

ASSESSMENT EXPECTATION ASSESSED MATH PRACTICES EXPECTATION ASSESSED
Balanced and Equal
Check-In:
Questions 6–8
with Feedback Box
Student Activity Book
Pages 399–400
E1.
Compose and decompose numbers using ones, fives, tens, twenties, fifties, and hundreds.
E4.
Recognize that different partitions of a number have the same total
(e.g., 50 + 4 = 40 + 14).
E5.
Apply the properties of addition (e.g., commutative, associative) to write number sentences that represent mass.
MPE5.
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
DPP Item G
Using Ten
Teacher Guide - digital
E13.
Determine the unknown number in an addition or subtraction sentence relating three whole numbers for the facts in Group F.