Exploring Least Common Multiple

Grade Level

6th Grade

Duration

30 minutes

Unit

Mastering GCF, LCM & Distributive (Lesson 2 of 4)

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Common Core State Standards

CCSS.MATH.CONTENT.6.NS.B.4
Find the least common multiple (LCM) of two whole numbers less than or equal to 100 and the greatest common factor (GCF) of two whole numbers less than or equal to 100 by listing multiples. Use the distributive property to express a sum of two whole numbers 1–100 with a common factor as a multiple of a sum of two whole numbers with no common factor.

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Learning Objectives – "I Can" Statements

• I can explain what the Least Common Multiple (LCM) means.
• I can find the LCM of two numbers by listing their multiples and skip counting.
• I can use sentence frames to explain how I found the LCM.
• I can solve LCM problems accurately for numbers up to 100.

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Success Criteria

• Correctly identify multiples of given numbers using skip counting and charts.
• Accurately find the LCM of given pairs of numbers by comparing multiples.
• Use sentence frames to clearly explain thinking and strategies with peers.
• Show understanding through group work and independent practice.

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Materials Needed

• Whiteboard and markers
• Skip Counting and Multiples Visual Charts (large, dyslexia-friendly with color-coding and clear fonts)
• Individual student whiteboards or notebooks
• Sentence Frame Cards (e.g., “The LCM of ___ and ___ is ___ because ___.”)
• LCM task cards with pairs of numbers up to 50
• Optional: Color pencils or markers for highlighting multiples
• Timer

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Lesson Outline

1. Introduction (5 minutes)

• Begin with a brief review of multiples (ask students to skip count aloud by 3s and 4s). Use the visual chart on the board.
• Display the term “Least Common Multiple” and ask what they think it could mean.
• Give the formal definition: The smallest multiple that two numbers share.
• Write an "I can" statement on the board:
  Today, I can find the Least Common Multiple of two numbers by listing their multiples.

2. Guided Discovery and Modeling (8 minutes)

• Model finding the LCM of 3 and 4 using skip counting:
  3, 6, 9, 12, 15…; 4, 8, 12, 16…
• Highlight 12 as the smallest common multiple. Highlight on the chart using color.
• Use sentence frames aloud:
  The multiples of 3 are ___. The multiples of 4 are ___. The smallest multiple they both share is ___. So, LCM(3,4) = 12.
• Demonstrate on the whiteboard and have students repeat sentence frames together.

3. Partner Activity: Practice with Task Cards (10 minutes)

• Divide students into pairs, providing each pair with a set of 5 task cards (each with 2 numbers under 50).
• Students work together to list multiples for each number on mini whiteboards or notebooks and find the LCM.
• Encourage use of sentence frames to explain their solutions to each other. Provide printed sentence frame cards for reference.
• Teacher circulates to scaffold, especially for students who need support with skip counting or organizing multiples visually (use color-coded charts).

4. Group Sharing & Discussion (5 minutes)

• Regroup as a class and invite 2-3 pairs to share their strategies and answers using the sentence frame:
  The LCM of ___ and ___ is ___. I found the LCM by ___.
• Use this time to reinforce correct methods and gently correct misconceptions.

5. Independent Challenge & Wrap-Up (2 minutes)

• Assign a quick independent question on the board (e.g., LCM of 6 and 8) for students to solve silently.
• Ask students to write a complete sentence using the sentence frame about how they found the LCM.
• End with a “thumbs up/thumbs down” self-assessment:
  Do you feel confident finding the LCM by listing multiples?

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Differentiation Strategies

Learner Type	Strategy	Details
Diverse Learners (including dyslexia)	Visual supports	Use color-coded multiples charts with dyslexia-friendly fonts; allow use of colored pencils for organizing multiples visually.
Students needing extra support	Small group reteach	Work in small groups after lesson with manipulatives such as number tiles or focused skip counting games.
Advanced Learners	Extension Tasks	Solve LCM problems with numbers up to 100 or word problems (e.g., finding LCM to determine event timing). Encourage use of prime factorization to find LCM.

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Dyslexia-Friendly Features

• Use sans-serif fonts (e.g., Arial or Comic Sans) on all printed charts and sentence frames.
• Color-code different multiples for clarity (e.g., multiples of 3 in red, multiples of 4 in green).
• Provide written and oral directions clearly and slowly.
• Use consistent, simple sentence frames to reinforce language.

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Assessment

• Formative: Observe students during partner work and listen for correct use of language and understanding.
• Check independent challenge answer and sentence for accuracy and explanation.
• Use exit thumbs-up/down to gauge confidence for reteach or advance.

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Teacher Reflection (Post-lesson)

• Were students able to list multiples systematically?
• Did sentence frames support students in articulating their mathematical thinking?
• Did diverse learners benefit from visual aids and group work?
• How did advanced learners respond to extension questions?

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This lesson plan empowers 6th graders to build a strong conceptual and strategic understanding of LCM, encouraging multiple ways to express mathematical thinking aligned tightly with CCSS standards in an engaging, accessible manner.