Multiplying Decimals

Grade: 6 | Duration: 30 minutes | Class Size: 13 students

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Unit: Mastering Numbers & Ratios

Lesson 4 of 30

Topic: Multiplying Decimals: Understanding the Process

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Common Core State Standards (CCSS) Alignment

• CCSS.MATH.CONTENT.6.NS.B.3
  Apply and extend previous understandings of multiplication and division to multiply and divide fractions.
  Note: This includes decimals as a subset of rational numbers.

• CCSS.MATH.CONTENT.6.NS.B.2
  Fluently divide multi-digit numbers using the standard algorithm.

• CCSS.MATH.CONTENT.6.EE.A.2
  Write, read, and evaluate expressions in which letters stand for numbers.

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Learning Objectives

By the end of this lesson, students will be able to:

• I can multiply decimals accurately by whole numbers and decimals.
• I can estimate the product of decimals to check reasonableness.
• I can explain the placement of the decimal point in a multiplication product.

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Success Criteria

I know I am successful when I can:

• Correctly multiply decimals and place the decimal point without error.
• Use rounding and estimation strategies before calculating to predict the product's approximate size.
• Verbally explain or write how the decimal placement changes in the product.

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Materials Needed

• Whiteboard and markers
• Individual student mini-whiteboards and dry-erase markers
• Base-10 decimal grids (printed)
• Place value charts (printed)
• Number line posters
• Multiplying Decimals anchor chart (prepared prior)
• Colored pencils or highlighters for dyslexia-friendly notes
• Worksheet with multiplying decimals problems (with dyslexia-friendly font and spacing)

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Lesson Outline

1. Hook (5 minutes): “Decimal Estimation Challenge”

• Pose a question verbally and visually: What is approximately 4.7 × 3.2?
• Students use mini whiteboards to write estimates by rounding decimals to nearest whole numbers (5 × 3 =15).
• Highlight how estimation helps with mental math and checking answers.
• Briefly discuss that today they will multiply decimals accurately and learn about decimal placement in the product.

Differentiation:

• Students struggling with place value can use the place value chart to support rounding and estimation.
• Use color coding for rounding decimals to make the concept clear.

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2. Direct Instruction (10 minutes): “Understanding the Multiplying Process”

• Write a multiplication problem on the board: 4.7 × 3.2
• Demonstrate ignoring the decimals initially: Multiply 47 by 32 like whole numbers.
• Show step-by-step multiplication (long algorithm) on the board.
• Count total decimal places in factors (one decimal place in 4.7 and one in 3.2 = two decimal places total).
• Explain using place value chart how decimal point in the product moves two places from the right.
• Use printed base-10 decimal grids to visualize the product (cross-shading grids equal to each factor).
• Write down the decimal product: 15.04

Dyslexia-Friendly Tip:

• Use colored overlays or highlight decimal points and place values in different colors to assist students in visualizing decimals.

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3. Guided Practice (8 minutes): “Multiplying Decimals with Support”

• Give students several problems on their mini whiteboards (e.g., 2.5 × 0.4, 1.2 × 3.3).
• Ask students to:
  • Estimate the product first.
  • Multiply ignoring decimals.
  • Place the decimal point correctly in answer.
• Circulate and offer assistance, checking for misconceptions.
• Invite volunteers to explain their decimal point placement on the board.

Differentiation:

• Provide place value charts and base-10 grids for students needing visual or tactile support.
• For students excelling, ask them to multiply decimals with three decimal places (e.g., 0.123 × 4.56).

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4. Independent Practice and Assessment (5 minutes):

• Distribute a short worksheet of 5 multiplying decimals problems with space for estimation, multiplication, and explanation of decimal placement.
• Students complete independently as a formative assessment.
• Encourage them to highlight or underline decimals during work for focus.

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5. Closure & Reflection (2 minutes): “I Can Statements Review”

• Revisit the I can statements aloud:
  • “I can multiply decimals accurately.”
  • “I can estimate decimal products.”
  • “I can explain decimal placement.”
• Quick thumbs up/down/thumbs middle for confidence check.
• Invite 1-2 students to share what helped them understand decimal placement.

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Extension Activities (Advanced Learners)

• Multiply two decimals where both have three decimal places (e.g., 0.456 × 0.789).
• Explore multiplying decimals leading to product less than 1 (e.g., 0.3 × 0.2).
• Challenge to represent decimal multiplication on number lines and explain interacting intervals.

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Differentiation Strategies

Learner Type	Strategy
Struggling Learners	Use place value charts, colored overlays, step-by-step scaffolded worksheets.
ELL Students	Provide visual aids, model vocabulary (e.g., “decimal point,” “estimate”).
Dyslexic Students	Dyslexia-friendly font handouts, highlight decimals in contrasting colors.
Advanced Learners	Provide complex decimals and word problems involving decimal multiplication.

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Teacher Reflection (Post-Lesson)

• Did students use estimation effectively to predict products?
• Were misconceptions about decimal placement minimized?
• Did hands-on decimal grids improve conceptual understanding?
• Which students require additional support or enrichment?

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End of Lesson