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Math lesson plan · 5th grade (Year 6 in England) · 45 minutes

Common multiples and the lowest common multiple

Number sense

CCSS 6.NS.B.4England: Y6 Number – multiplication and division

Objective and success criteria

Students will: Common multiples and the lowest common multiple.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Recognise multiples of a number

Leads to: the next skill in this area.

Materials: Place value chart, Base-ten blocks or a number line, Mini whiteboards and pens, Printed student sheet (below).

Warm-up · 5 min

  • Quick retrieval from earlier learning (Recognise multiples of a number). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which is a multiple of 3? (25 / 26 / 24 / 22) → 24Prompt: A multiple of 3 is in the 3 times table (or beyond it).
  2. How many multiples of 12 are there from 1 to 37? → 3Prompt: What is the biggest multiple of 12 that is not more than 37?
  3. Hana says 127 is a multiple of 6. True or false? (true / false) → falsePrompt: Divide 127 by 6.

Hook · 5 min

  • Show a number in the news or a price tag and ask what each digit is worth.
  • Share the objective: Common multiples and the lowest common multiple. Read the success criteria together.

I do: model it · 10 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: What is the lowest common multiple of 3 and 4?
  • Step 1: Multiples of 4: 4, 8, 12, 16, 20
  • Step 2: 12
  • Answer: 12
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 10 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. What is the lowest common multiple of 6 and 10? → 30Prompt: List multiples of 10: 10, 20, 30, …
  2. Two buses leave the station together at 7:00. One leaves every 6 minutes and the other every 10 minutes. After how many minutes do they next leave together? → 30Prompt: You need a time that is in both lists of departure times.

You do: independent practice · 10 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. What is the lowest common multiple of 6 and 10? → 30Prompt: List multiples of 10: 10, 20, 30, …
  2. Two buses leave the station together at 10:00. One leaves every 6 minutes and the other every 8 minutes. After how many minutes do they next leave together? → 24Prompt: You need a time that is in both lists of departure times.

Watch out for

  • Reading 1,045 as one thousand four hundred five: point to each place and say its value.
  • Thinking a longer number is always bigger, even with decimals (0.45 vs 0.5).

Support and stretch

Support

  • Review first: Recognise multiples of a number.
  • Use concrete materials: place value chart.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-5.

Free lesson plan from eurekami.com/lesson-plan-builder

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Common multiples and the lowest common multiple

Name

Date

Score/ 8

  1. Question 1

    Two buses leave the station together at 9:00. One leaves every 15 minutes and the other every 20 minutes. After how many minutes do they next leave together?

    Answer

  2. Question 2

    What is the lowest common multiple of 6 and 8?

    Answer

  3. Question 3

    Two buses leave the station together at 10:00. One leaves every 15 minutes and the other every 20 minutes. After how many minutes do they next leave together?

    Answer

  4. Question 4

    What is the lowest common multiple of 4 and 10?

    Answer

  5. Question 5

    Two buses leave the station together at 7:00. One leaves every 6 minutes and the other every 10 minutes. After how many minutes do they next leave together?

    Answer

  6. Question 6

    What is the lowest common multiple of 4 and 6?

    Answer

  7. Question 7

    Two buses leave the station together at 8:00. One leaves every 9 minutes and the other every 12 minutes. After how many minutes do they next leave together?

    Answer

  8. Question 8

    Two buses leave the station together at 10:00. One leaves every 8 minutes and the other every 12 minutes. After how many minutes do they next leave together?

    Answer

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Answer key: Common multiples and the lowest common multiple

  1. 1. 60

  2. 2. 24

  3. 3. 60

  4. 4. 20

  5. 5. 30

  6. 6. 12

  7. 7. 36

  8. 8. 24