Lesson 3

Explore Subtraction Word Problems

Est. Class Sessions: 2
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Mathematical Standards

2.MD.B
Relate addition and subtraction to length. (2.MD.B.6)
2.OA.A
Represent and solve problems involving addition and subtraction. (2.OA.A.1)
2.OA.B
Add and subtract within 20. (2.OA.B.2)
2.NBT.A
Understand place value. (2.NBT.A.1)
2.NBT.B
Use place value understanding and properties of operations to add and subtract. (2.NBT.B.5, 2.NBT.B.7, 2.NBT.B.8)

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.
MP5.
Use appropriate tools strategically.

Students solve different types of take away and comparison subtraction problems. They look at important information in each problem and discuss strategies and tools to solve them. After looking at models of subtraction word problems, students write their own problems.

Content in this Lesson

  • Representing subtraction using multiple representations (e.g., stories, drawings, diagrams, counters, number sentences, number lines,
    ten frames) [E3].
  • Solving subtraction problems using counting strategies and related addition facts [E5].
  • Using mental math strategies and reasoning strategies (e.g., using doubles, using ten, making ten, reasoning from known facts) to solve subtraction problems within 20 [E6].
  • Solving word problems (separate/take away and compare) involving two whole numbers with a sum within 100 using counters, drawings, number lines, and number sentences [E7].
  • Knowing what is important to solve a problem [MPE1].
  • Choosing good tools and strategies to solve a problem [MPE2].
  • Checking for reasonableness [MPE3].
  • Showing or telling solution strategies [MPE5].
  • Using labels to show what numbers mean [MPE6].
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Materials for Students

Daily Practice and Problems Lesson Homework Assessment

Student Book

 Student Activity Book

Teacher Resources

 Teacher Guide - digital

Supplies for Students

20 connecting cubes
desk number line (0–100)

Materials for the Teacher

Display of Math Practices (Student Activity Book) Reference
Display of Subtraction Problem Types: Separate/Take Away Master (Teacher Guide)
Display of Subtraction Problem Types: Compare Master (Teacher Guide)
Display of Write a Word Problem Masters (Teacher Guide)
Unit 3 Assessment Record
chart paper. See Materials Preparation.
connecting cubes

Materials Preparation

Prepare Display for Carnival Word List. Prepare a piece of chart paper with the title “Carnival Rides and Activities.” Students will generate a list of words to use as they write their own problems.

Assessment in this Lesson

ASSESSMENT EXPECTATION ASSESSED MATH PRACTICES EXPECTATION ASSESSED
Can You Solve It
with Feedback Box
Student Activity Book
Pages 117–120
E3.
Represent addition and subtraction using multiple representations (e.g., stories, drawings, diagrams, counters, number sentences, number lines,
200 Chart).
E5.
Solve subtraction problems using counting strategies.
E6.
Use mental math strategies and reasoning strategies (e.g., using doubles, using ten, making ten, reasoning from known facts) to solve addition and subtraction problems within 20.
E7.
Solve word problems (e.g., join, separate/take away, part-whole, compare) involving two whole numbers with a sum within 100 using counters, drawings, 200 Chart, and number lines.
MPE1. 
Know the problem. I read the problem carefully. I know the questions to answer and what information is important.
MPE2. 
Find a strategy. I choose good tools and an efficient strategy for solving the problem.
MPE3. 
Check for reasonableness. I look back at my solution to see if my answer makes sense. If it does not, I try again.
MPE5.
Show my work. I show or tell how I arrived at my answer so someone else can understand my thinking.
MPE6.
Use labels. I use labels to show what numbers mean.