Math lesson plan · 5th grade (Year 6 in England) · 45 minutes
Simplify fractions in one step using the greatest common factor
Fractions
CCSS 6.NS.B.4England: Y6 Fractions
Objective and success criteria
Students will: Simplify fractions in one step using the greatest common factor.
- 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: Write a fraction in its simplest form
Leads to: the next skill in this area.
Materials: Fraction strips or a fraction wall, Paper strips to fold, Number lines, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Write a fraction in its simplest form). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Simplify 3/9. → 1/3Prompt: Find a number that divides both the top and the bottom.
- Nia says 3/12 is in its simplest form. True or false? (true / false) → falsePrompt: Is there a number other than 1 that divides both 3 and 12?
- 15 out of 24 pupils in a class have a pet. What fraction is that, in its simplest form? → 5/8Prompt: Start with 15/24.
Hook · 5 min
- Cut a pizza or a strip of paper unevenly and ask whether the pieces are really halves or quarters.
- Share the objective: Simplify fractions in one step using the greatest common factor. 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: Simplify 48/156 fully.
- Step 1: The greatest common factor is 12.
- Step 2: 48/156 = 4/13
- Answer: 4/13
- 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.
- Simplify 80/112 fully. → 5/7Prompt: Find the greatest number that divides both.
- Ines simplified 18/72 to 2/8 and stopped. Is that in simplest form? If not, finish it. What is the simplest form? → 1/4Prompt: Do 2 and 8 still share a factor?
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.
- Simplify 36/42 fully. → 6/7Prompt: Find the greatest number that divides both.
- Kwame simplified 24/36 to 4/6 and stopped. Is that in simplest form? If not, finish it. What is the simplest form? → 2/3Prompt: Do 4 and 6 still share a factor?
Watch out for
- Thinking a bigger denominator means a bigger fraction (1/8 > 1/4).
- Adding the denominators when adding fractions (1/2 + 1/3 = 2/5).
Support and stretch
Support
- Review first: Write a fraction in its simplest form.
- Use concrete materials: fraction strips or a fraction wall.
- 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