Math lesson plan · 5th grade (Year 6 in England) · 45 minutes
Word problems with unlike denominators
Fractions
CCSS 5.NF.A.2England: Y6 Fractions
Objective and success criteria
Students will: Word problems 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 unlike denominators
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 (Add and subtract fractions with unlike denominators). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 3/4 + 3/8 = ? Give your answer in simplest form. → 9/8 (1 1/8)Prompt: You need a common denominator first.
- 3/5 − 3/10 = ? Give your answer in simplest form. → 3/10Prompt: Find a common denominator.
- Yuki ran 2/3 of a mile and then 5/12 of a mile. How far did Yuki run altogether? (Simplest form; an improper fraction is fine.) → 13/12 (1 1/12)Prompt: Add the two distances.
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: Word problems 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: Chloe spends 1/4 of an hour on maths homework and 4/5 of an hour reading. What fraction of an hour is that altogether?
- Step 1: 1/4 = 5/20, 4/5 = 16/20
- Step 2: 5/20 + 16/20 = 21/20
- Step 3: 1 1/20
- Answer: 21/20 (1 1/20)
- 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.
- Felix spends 2/3 of an hour on maths homework and 3/4 of an hour reading. What fraction of an hour is that altogether? → 17/12 (1 5/12)Prompt: Use the common denominator 12.
- A garden is planted: 1/2 with vegetables and 1/5 with flowers. The rest is grass. What fraction is grass? → 3/10Prompt: Add the planted parts using denominator 10.
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.
- Without calculating exactly: is 1/2 + 2/5 less than 1, more than 1, or exactly 1? (less than 1 / more than 1 / exactly 1) → less than 1Prompt: Compare each fraction with 1/2.
- Mateo spends 1/3 of an hour on maths homework and 3/5 of an hour reading. What fraction of an hour is that altogether? → 14/15Prompt: Use the common denominator 15.
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 unlike 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
- 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