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Math lesson plan · 4th grade (Year 5 in England) · 60 minutes

Find factor pairs of a number

Number sense

CCSS 4.OA.B.4England: Y5 Multiplication and division

Objective and success criteria

Students will: Find factor pairs of a number.

  • 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: Factors, multiples, primes

Leads to: Recognise multiples of a number; Prime or composite?; Common factors of two numbers

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

Warm-up · 6 min

  • Quick retrieval from earlier learning (Factors, multiples, primes). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which number is a factor of 30? (3 / 12 / 7 / 11) → 3Prompt: A factor divides the number exactly, with no remainder.
  2. Is 49 prime or composite? (Prime / Composite) → CompositePrompt: A prime number has exactly two factors: 1 and itself.
  3. What is the 10th multiple of 3? (The 1st multiple is 3.) → 30Prompt: Multiples of 3: 3, 6, 9, …

Hook · 6 min

  • Show a number in the news or a price tag and ask what each digit is worth.
  • Share the objective: Find factor pairs of a number. Read the success criteria together.

I do: model it · 12 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: 6 × __ = 60. Complete the factor pair.
  • Step 1: 60 ÷ 6 = 10
  • Step 2: 6 × 10 = 60
  • Answer: 10
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 12 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. 2 × __ = 72. Complete the factor pair. → 36Prompt: What do you multiply 2 by to get 72?
  2. How many factors does 20 have? (Count 1 and 20 too.) → 6Prompt: List factor pairs: 1 × ?, 2 × ?, 3 × ? …

You do: independent practice · 17 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 · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Ines is arranging 48 photos in a rectangle with no gaps. Which layout works? (2 × 24 / 24 × 3 / 3 × 24 / 2 × 25) → 2 × 24Prompt: Rows × columns must equal 48.
  2. 2 × __ = 28. Complete the factor pair. → 14Prompt: What do you multiply 2 by to get 28?

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: Factors, multiples, primes.
  • 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

  • Move on to: Recognise multiples of a number; Prime or composite?; Common factors of two numbers.
  • 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-4.

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

eurekami

Find factor pairs of a number

Name

Date

Score/ 8

  1. Question 1

    How many factors does 30 have? (Count 1 and 30 too.)

    Answer

  2. Question 2

    Arjun is arranging 36 photos in a rectangle with no gaps. Which layout works?

    • A. 2 × 19
    • B. 3 × 18
    • C. 18 × 3
    • D. 2 × 18
  3. Question 3

    2 × __ = 16. Complete the factor pair.

    Answer

  4. Question 4

    Felix is arranging 24 photos in a rectangle with no gaps. Which layout works?

    • A. 3 × 8
    • B. 3 × 9
    • C. 4 × 8
    • D. 12 × 3
  5. Question 5

    3 × __ = 45. Complete the factor pair.

    Answer

  6. Question 6

    How many factors does 16 have? (Count 1 and 16 too.)

    Answer

  7. Question 7

    Mei is arranging 60 photos in a rectangle with no gaps. Which layout works?

    • A. 4 × 20
    • B. 30 × 3
    • C. 3 × 21
    • D. 3 × 20
  8. Question 8

    3 × __ = 48. Complete the factor pair.

    Answer

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Answer key: Find factor pairs of a number

  1. 1. 8

  2. 2. D. 2 × 18

  3. 3. 8

  4. 4. A. 3 × 8

  5. 5. 15

  6. 6. 5

  7. 7. D. 3 × 20

  8. 8. 16