Adding and Subtracting Decimals

Grade Level

6th Grade

Duration

30 minutes

Unit

Mastering Numbers & Ratios
Lesson 2 of 30

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Common Core State Standards Addressed

CCSS.MATH.CONTENT.6.NS.B.3
Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation.

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Learning Objectives

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

• I can add multi-digit decimals accurately using place value understanding.
• I can subtract multi-digit decimals correctly by aligning decimal points.
• I can explain why lining up decimal points is important in adding and subtracting decimals.

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Success Criteria

Students will demonstrate mastery when they can:

• Correctly solve at least 5 multi-digit decimal addition and subtraction problems independently.
• Verbally explain the reasoning behind lining up decimal points when adding or subtracting decimals.

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Materials Needed

• Whiteboard and markers
• Base-ten decimal place value charts (printed for each student)
• Decimal addition and subtraction worksheets (dyslexia-friendly font and spacing)
• Number lines (optional for visual aid)
• Dry erase boards and markers for each student
• Sticky notes for quick exit tickets

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Lesson Breakdown

1. Introduction & Review (5 minutes)

• Begin with a quick 2-minute warm-up: Ask students to recall the place value positions in decimals (tenths, hundredths, thousandths).
• Use a base-ten decimal place value chart projected on the board or printed for students.
• Briefly review previous lesson's major concepts on place value to build a foundation.
• Write the “I can” statements and the learning goal on the board.

2. Guided Practice– Adding Decimals (8 minutes)

• Model adding decimals with 2 examples on the whiteboard using multi-digit decimals (e.g., 12.356 + 3.47).
• Emphasize lining up the decimal points, using place value language (tenths under tenths, hundredths under hundredths).
• Use a dry erase board and have students try a similar problem with you, step by step.
• Use verbal prompts: "What digit lines up next to this number?" and "What do we do if one number has more decimal places?"
• Highlight common mistakes (e.g., misalignment of decimal points).
• Ask students to explain why lining up decimals is critical in pairs for 1 minute.

3. Guided Practice– Subtracting Decimals (7 minutes)

• Repeat the same process as above with subtraction (e.g., 15.607 – 4.39).
• Model borrowing across place values if needed.
• Use a visual number line to demonstrate subtraction of decimals for students who need it.
• Check for understanding by asking students to solve one problem independently on their dry erase boards.
• Address mistakes and misconceptions as they arise.

4. Independent Practice (7 minutes)

• Hand out worksheets with 5 problems combining both adding and subtracting multi-digit decimals.
• Have students work independently while monitoring and providing support as needed.
• Encourage them to use their place value charts and line up decimals carefully.
• Students who finish early can start on the extension activity or create their own decimal addition/subtraction problems for a partner to solve.

5. Wrap-Up & Assessment (3 minutes)

• Ask students to use sticky notes to write down: "One thing I learned about adding and subtracting decimals" and “One question I still have.”
• Quickly review a couple of sticky notes aloud to clarify questions.
• Reinforce the importance of decimal alignment.
• Preview the next lesson briefly.

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Differentiation Strategies

Learner Type	Adaptations & Supports
Struggling learners	Use number lines and place value charts; provide step-by-step guided examples; pair with a peer tutor; allow extra time.
Advanced learners	Provide problems with more decimal places (thousandths and beyond); introduce real-world word problems involving money or measurement.
Dyslexic learners	Provide worksheets in dyslexia-friendly fonts (open sans, larger spacing), use high contrast colors; verbalize each step clearly; minimize distractions.
EAL (English as an Additional Language)	Use visual aids and gestures; write key vocabulary on the board; allow verbal or visual responses.

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Extension Activity

• Challenge advanced students to solve multi-step problems involving adding and subtracting decimals in real-life contexts (e.g., shopping receipts, measurements in science).
• Invite students to create a short video or comic strip explaining how to add and subtract decimals, emphasizing decimal alignment.

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This lesson plan balances hands-on, visual, and verbal learning strategies while adhering strictly to the Common Core standards for 6th grade math fluency with decimals. The inclusion of "I can" statements and success criteria empowers students and informs teaching. Differentiation ensures every learner is supported and engaged.