Lesson 8

Workshop: Subtraction Practice

Est. Class Sessions: 2
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Mathematical Standards

2.NBT.A
Understand place value. (2.NBT.A.1, 2.NBT.A.2)
2.NBT.B
Use place value understanding and properties of operations to add and subtract. (2.NBT.B.6, 2.NBT.B.7, 2.NBT.B.8, 2.NBT.B.9)
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)

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.
MP7.
Look for and make use of structure.
MP8.
Look for and express regularity in repeated reasoning.

Students practice a variety of mental math and paper-and-pencil subtraction methods with multidigit numbers. They estimate and check for reasonableness, and explore the efficiency and usefulness of the strategies in various situations.

Content in this Lesson

  • Solving multidigit subtraction problems using mental math strategies
    (e.g., composing and decomposing numbers, counting up) with number lines, a 200 Chart, and base-ten pieces [E3].
  • Solving multidigit subtraction problems using paper-and-pencil methods
    (e.g., expanded form, compact) [E4].
  • Using and applying place value concepts to make connections among representations of numbers using base-ten pieces, number lines, expanded form, and standard form [E1].
  • Representing subtraction problems using base-ten pieces and number
    lines [E2].
  • Choosing good tools and efficient strategies for different types of
    problems [MPE2].
  • Determining the reasonableness of a solution to a subtraction problem [MPE3].
  • Solving problems in a variety of ways to check subtraction
    calculations [MPE4].
  • Solving subtraction problems and showing the solution strategy [MPE5].
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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

base-ten pieces (21 bits, 20 skinnies, 5 flats)
Subtraction Strategies Menu from Lesson 7, optional

Materials for the Teacher

Display of Subtraction Strategies Menu (Student Activity Book) Reference
Display of Subtraction Practice Workshop Menu (Student Activity Book) Page 479
Display of Game 1 of Difference War (Student Activity Book) Pages 487–488
Display of What Went Wrong Master (Teacher Guide)
Unit 9 Assessment Record
Subtraction Strategies Chart from Lesson 2
6–8 prepared additional sets of Digit Cards 0–9 Master (Teacher Guide). See Materials Preparation.
envelopes or small reasonable bags
scissors

Materials Preparation

Prepare Digit Cards. Students will play Difference War in groups of two. Each group needs 4 sets of the Digit Cards 0–9 Master for Game 1. The decks of digit cards from Unit 7 may be used, or you can copy and cut new sets. Prepare 6–8 additional sets of digit cards for students who choose to play Game 2 of Difference War so that players will have 6 sets per game.

Assessment in this Lesson

Assessment Expectation Assessed Math Practices Expectation Assessed
Subtraction Practice Workshop Menu
Self-Check
Student Activity Book
Page 479
E1. 
Use and apply place value concepts to make connections among representations of numbers to the thousands using base-ten pieces, number lines, expanded form, and standard form.
E2. 
Represent subtraction problems using base-ten pieces and number lines.
E3. 
Subtract multidigit numbers using mental math strategies (e.g., composing and decomposing numbers, counting up) with number lines, a
200 Chart, and base-ten pieces.
E4. 
Subtract multidigit numbers using
paper-and-pencil methods (e.g., expanded form, compact).
Subtraction Strategies Quiz
with Feedback Box
Student Activity Book
Pages 491–493
E1. 
Use and apply place value concepts to make connections among representations of numbers to the thousands using base-ten pieces, number lines, expanded form, and standard form.
E3. 
Subtract multidigit numbers using mental math strategies (e.g., composing and decomposing numbers, counting up) with number lines, a
200 Chart, and base-ten pieces.
E4. 
Subtract multidigit numbers using
paper-and-pencil methods (e.g., expanded form, compact).
E5. 
Estimate differences using mental math strategies (e.g., rounding using benchmarks, using friendly numbers, composing and decomposing numbers, counting on).
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.
MPE4. 
Check my calculations. If I make mistakes, I correct them.

Vocabulary in this Lesson