Lesson 3

Parts and Wholes

Est. Class Sessions: 2-3
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Mathematical Standards

1.NBT.A
Extend the counting sequence. (1.NBT.A.1)
1.OA.A
Represent and solve problems involving addition and subtraction. (1.OA.A.1, 1.OA.A.2)
1.OA.C
Add and subtract within 20. (1.OA.C.5, 1.OA.C.6)
1.OA.D
Work with addition and subtraction equations. (1.OA.D.7)

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.
MP6.
Attend to precision.
MP8.
Look for and express regularity in repeated reasoning.

Students write addition number sentences for the numbers 11 and 12 and partition numbers into two or more addends. Students solve problems with missing addends.

Content in this Lesson

  • Composing and decomposing numbers using counters and number sentences [E1].
  • Representing addition situations with words and number sentences [E7].
  • Connecting representations of numbers [E4].
  • Solving addition problems using a counting-on strategy [E5].
  • Solving addition word problems involving two whole numbers whose sum is less than or or equal to 30 using tools (e.g., counters, number lines, calculators, diagrams, ten frames) [E6, MPE2].
  • Showing work so that others can understand their thinking [MPE5].
  • Solving problems another way to check for reasonableness and mistakes [MPE3, MPE4].
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Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Books

 Student Activity Book

Teacher Resources

 Teacher Guide - digital

Supplies for Students

about 20 connecting cubes or counters
scissors
desk number line (0–40)
calculator

Materials for the Teacher

Display of Two Partitions Master (Teacher Guide), optional
Display of Two Parts and the Whole Master (Teacher Guide)
Display of Three Partitions Master (Teacher Guide)
Display of Three Parts and the Whole Master (Teacher Guide)
Unit 4 Assessment Record
12 Ways to Get to 11 by Eve Merriam
20 connecting cubes or counters
chart paper for Ways to Make 11 and Ways to Make 12 charts. See Materials Preparation.
tape or glue stick

Materials Preparation

Make Charts. Prepare two charts on chart paper. Title one "Ways to Make 11" and the other "Ways to Make 12."

Prepare Optional Targeted Practice. Make a center activity using connecting cubes and copies of the Parts and Wholes pages. Students can choose their own numbers to partition, or you can write different numbers at the top of the first page.

Assessment in this Lesson

Assessment Expectation Assessed Math Practices Expectation Assessed
More Parts and Wholes
with Feedback Box
Teacher Guide - digital
E1. 
Compose and decompose numbers 1–20 using counters, drawings, ten frames, number lines, diagrams, and number sentences.
E7. 
Represent addition situations with stories, drawings, diagrams, counters, number lines, and number sentences.
MPE2. 
Find a strategy. I choose good tools and an efficient strategy for solving the problem.
MPE5. 
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
DPP Item J
Counting On Using the Ten Frame
Teacher Guide - digital
E3. 
Represent quantities using a ten frame, counters, pictures, number lines, and symbols.

Vocabulary in this Lesson