Math lesson plan · 4th grade (Year 5 in England) · 30 minutes
Prime or composite?
Number sense
CCSS 4.OA.B.4England: Y5 Multiplication and division
Objective and success criteria
Students will: Prime or composite?.
- 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: 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 · 4 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.
- 4 × __ = 64. Complete the factor pair. → 16Prompt: What do you multiply 4 by to get 64?
- How many factors does 36 have? (Count 1 and 36 too.) → 9Prompt: List factor pairs: 1 × ?, 2 × ?, 3 × ? …
- Diego is arranging 36 photos in a rectangle with no gaps. Which layout works? (3 × 13 / 4 × 12 / 3 × 12 / 18 × 3) → 3 × 12Prompt: Rows × columns must equal 36.
Hook · 3 min
- Show a number in the news or a price tag and ask what each digit is worth.
- Share the objective: Prime or composite?. Read the success criteria together.
I do: model it · 7 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Is 25 prime or composite?
- Step 1: Factors of 25: 1, 5, 25
- Step 2: composite
- Answer: composite
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 6 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- Is 55 prime or composite? (prime / composite) → compositePrompt: A prime has exactly two factors: 1 and itself.
- Which of these numbers is prime? (33 / 71 / 21 / 91) → 71Prompt: Odd numbers can still be composite: try 3, 7 and 9.
You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.
Exit ticket · 3 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Is 16 prime or composite? (prime / composite) → compositePrompt: A prime has exactly two factors: 1 and itself.
- Luis says: "21 is prime." True or false? (true / false) → falsePrompt: List the factors of the number.
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
- 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