Lesson 10

Strategies for Multiplying Decimals

Est. Class Sessions: 3
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Mathematical Standards

5.NBT.A
Understand the place value system. (5.NBT.A.1, 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

MP1.
Make sense of problems and persevere in solving them.
MP2.
Reason quantitatively.
MP3.
Construct viable arguments and critique the reasoning of others.
MP4.
Model with mathematics.
MP5.
Use appropriate tools strategically.
MP6.
Attend to precision.
MP7.
Look for and make use of structure.
MP8.
Look for and express regularity in repeated reasoning.

Students explore the multiplication of decimals. They solve problems using models and paper-andpencil strategies. They learn to use two methods to place the decimal point in the product, including estimating the product. Students estimate decimal products as they play the Three in a Row game.

Content in this Lesson

  • Multiplying and dividing decimals using models and strategies [E8].
  • Estimating decimal products [E9].
  • Recognizing that in a multidigit number, a digit in one place represents 10 times as much as it represents in the place to its right and 1/10 of what it represents in the place to its left [E5].
  • Explaining the patterns in the number of zeros of the product when multiplying by a number by powers of 10 [E6].
  • Explaining patterns in the placement of the decimal point when a decimal is multiplied by a power of ten [E6].
  • Representing numbers to the thousandths using symbols, words, area models, base ten pieces, and expanded form [E1].
  • Finding a strategy [MPE2].
  • Checking 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
  • calculator
  • 8–10 game markers of one color or shape

Materials for the Teacher

Assessment in this Lesson

Assessment Expectation Assessed Math Practices Expectation Assessed

Strategies for Multiplying Decimals
Check-In:
Questions 14–17
Student Guide
Page 403
and the corresponding
Feedback Box
Teacher Guide - digital
E5.
Recognize that in a multidigit number, a digit in one place represents 10 times as much as it represents in the place to its right and 1/10 of what it represents in the place to its left.
E6.
Explain the patterns in the number of zeros of the product when multiplying a number by powers of 10, and explain patterns in the placement of the decimal point when a decimal is multiplied or divided by a power of ten.

Strategies for Multiplying Decimals
Check-In: Question 31
Student Guide
Page 409
E8.
Multiply and divide decimals using models and strategies.
E9.
Estimate sums, differences, products, and quotients involving decimals and fractions.
MPE2.
Find a strategy. I choose good tools and an efficient strategy for solving the problem.