Math lesson plan · 5th grade (Year 6 in England) · 45 minutes
Add and subtract fractions with unlike denominators
Fractions
CCSS 5.NF.A.1CCSS 5.NF.A.2England: Y5 FractionsEngland: Y6 Fractions
Objective and success criteria
Students will: Add and subtract fractions with unlike denominators.
- 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: Add and subtract fractions with like denominators; Equivalent fractions; Factors, multiples, primes
Leads to: Operations with negative fractions and decimals; Add and subtract mixed numbers; Algebraic fractions
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 (Add and subtract fractions with like denominators; Equivalent fractions; Factors, multiples, primes). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Which number is a factor of 32? (12 / 6 / 7 / 4) → 4Prompt: A factor divides the number exactly, with no remainder.
- Which number is a factor of 40? (12 / 10 / 9 / 6) → 10Prompt: A factor divides the number exactly, with no remainder.
- Which number is a factor of 36? (10 / 8 / 18 / 11) → 18Prompt: A factor divides the number exactly, with no remainder.
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: Add and subtract fractions with unlike denominators. 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: 5/6 + 11/12 = ? Give your answer in simplest form.
- Step 1: 5/6 = 10/12
- Step 2: 11/12 = 11/12
- Step 3: 10/12 + 11/12 = 21/12
- Step 4: = 7/4
- Answer: 7/4 (1 3/4)
- 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.
- 1/2 + 7/10 = ? Give your answer in simplest form. → 6/5 (1 1/5)Prompt: You need a common denominator first.
- 1/2 − 1/8 = ? Give your answer in simplest form. → 3/8Prompt: Find a common denominator.
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.
- 5/6 − 4/5 = ? Give your answer in simplest form. → 1/30Prompt: Find a common denominator.
- 2/3 + 7/12 = ? Give your answer in simplest form. → 5/4 (1 1/4)Prompt: You need a common denominator first.
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: Add and subtract fractions with like denominators.
- 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
- Move on to: Operations with negative fractions and decimals; Add and subtract mixed numbers; Algebraic fractions.
- 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