Math lesson plan · 5th grade (Year 6 in England) · 30 minutes
Subtract mixed numbers by regrouping a whole
Fractions
CCSS 5.NF.A.1England: Y6 Fractions
Objective and success criteria
Students will: Subtract mixed numbers by regrouping a whole.
- 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 mixed numbers with the same denominator; Subtract a fraction from a whole number
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 · 4 min
- Quick retrieval from earlier learning (Add and subtract mixed numbers with the same denominator; Subtract a fraction from a whole number). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- 2 1/3 + 4 2/3 = ? → 7Prompt: Add the whole numbers, then add the fractions.
- 3 3/4 − 1 2/4 = ? → 9/4 (2 1/4)Prompt: Subtract the whole numbers, then the fractions.
- 3 3/6 + 1 3/6 = ? → 5Prompt: Add the whole numbers, then add the fractions.
Hook · 3 min
- Cut a pizza or a strip of paper unevenly and ask whether the pieces are really halves or quarters.
- Share the objective: Subtract mixed numbers by regrouping a whole. 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: 5 1/4 − 2 2/4 = ?
- Step 1: 4 5/4 − 2 2/4
- Step 2: 2 3/4
- Step 3: 2 3/4
- Answer: 11/4 (2 3/4)
- 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.
- 8 3/5 − 5 4/5 = ? → 14/5 (2 4/5)Prompt: 3/5 is smaller than 4/5, so regroup one whole.
- A ribbon is 5 1/4 m long. Hiro cuts off 3 3/4 m. How much ribbon is left? → 3/2 (1 1/2)Prompt: You cannot take the fraction part away without regrouping.
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.
- A ribbon is 5 1/8 m long. Grace cuts off 1 3/8 m. How much ribbon is left? → 15/4 (3 3/4)Prompt: You cannot take the fraction part away without regrouping.
- 7 2/4 − 2 3/4 = ? → 19/4 (4 3/4)Prompt: 2/4 is smaller than 3/4, so regroup one whole.
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 mixed numbers with the same denominator.
- 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