Lesson 7

Strategies for Adding and Subtracting Decimals

Est. Class Sessions: 3
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Mathematical Standards

5.NBT.A
Understand the place value system. (5.NBT.A.3)
5.NBT.B
Perform operations with multi-digit whole numbers and with decimals to hundredths. (5.NBT.B.7)

Standards for Mathematical Practice

MP2.
Reason quantitatively.
MP6.
Attend to precision.
MP7.
Look for and make use of structure.

Students explore addition and subtraction of decimals using estimation, invented strategies, fraction circle pieces, base-ten pieces, hundredths circles, number lines, and hundredths grids. Students play a game involving moves on a number line to build strategies for composing, decomposing, adding, and subtracting decimals.

Content in this Lesson

  • Adding and subtracting decimals to the hundredths using models and strategies [E7].
  • Estimating decimal sums and differences [E9].
  • Representing numbers to the hundredths using circle pieces, grid models, base-ten pieces, number lines, symbols, and words [E1].
  • Making connections among representations of decimal numbers to the hundredths [E2].
  • Finding addition and subtraction strategies [MPE2].
  • Estimating to check for reasonableness [MPE3].
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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

  • fraction circle pieces
  • base-ten pieces
  • Hundredths Circle Wheel from Lesson 2

Supplies for Student Pairs

  • clear plastic spinner or paper clip and pencil

Materials for the Teacher

Materials Preparation

Prepare Optional Targeted Practice. Make extra copies of the Start, Hop, Stop to Hundredths Game Board Master, the Number Line Patterns 1 Master, and the Number Line Patterns 2 Master to provide targeted practice.

Assessment in this Lesson

Assessment Expectation Assessed Math Practices Expectation Assessed

Add and Subtract Decimals with Models and Strategies
with Feedback Box
Teacher Guide - digital
E1.
Represent numbers to the thousandths using fractions, decimals, words, area models, base-ten pieces, number lines, and expanded form.
E7.
Add and subtract decimals to the thousandths using models and strategies.
E9.
Estimate sums, differences, products, and quotients involving decimals and fractions.
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.

DPP Item S
Name the Facts
Teacher Guide - digital
E13.
Demonstrate fluency with the multiplication and division facts.