Math lesson plan · 4th grade (Year 5 in England) · 45 minutes
Common factors of two numbers
Number sense
CCSS 6.NS.B.4England: Y5 Multiplication and division
Objective and success criteria
Students will: Common factors of two numbers.
- 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: Find factor pairs of a number
Leads to: Write a fraction in its simplest form
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 (Find factor pairs of a number). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 3 × __ = 18. Complete the factor pair. → 6Prompt: What do you multiply 3 by to get 18?
- How many factors does 24 have? (Count 1 and 24 too.) → 8Prompt: List factor pairs: 1 × ?, 2 × ?, 3 × ? …
- Zoe is arranging 42 photos in a rectangle with no gaps. Which layout works? (2 × 22 / 3 × 21 / 2 × 21 / 21 × 3) → 2 × 21Prompt: Rows × columns must equal 42.
Hook · 5 min
- Show a number in the news or a price tag and ask what each digit is worth.
- Share the objective: Common factors of two numbers. 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: Which number is a common factor of 6 and 15?
- Step 1: Common factors: 1, 3
- Step 2: 3
- Answer: 3
- 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.
- Which number is a common factor of 9 and 12? (4 / 2 / 12 / 3) → 3Prompt: A common factor divides both numbers exactly.
- Zara has 4 pencils and 6 rubbers. Zara wants to make identical packs with no items left over. What is the greatest number of packs Zara can make? → 2Prompt: The number of packs must divide both 4 and 6.
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.
- Which number is a common factor of 18 and 30? (9 / 15 / 18 / 6) → 6Prompt: A common factor divides both numbers exactly.
- Priya has 10 pencils and 15 rubbers. Priya wants to make identical packs with no items left over. What is the greatest number of packs Priya can make? → 5Prompt: The number of packs must divide both 10 and 15.
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: Find factor pairs 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
- Move on to: Write a fraction in its simplest form.
- 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