Math lesson plan · 4th grade (Year 5 in England) · 45 minutes
Subtract a fraction from a whole number
Fractions
CCSS 4.NF.B.3.CEngland: Y5 Fractions
Objective and success criteria
Students will: Subtract a fraction from a whole number.
- 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: Whole numbers written as fractions; Add and subtract fractions with like denominators
Leads to: Subtract mixed numbers by regrouping a whole
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 (Whole numbers written as fractions; Add and subtract fractions with like denominators). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Write 4 as a fraction with denominator 1. What is the numerator? → 4Prompt: Each whole is 1/1.
- Write 9 as a fraction with denominator 1. What is the numerator? → 9Prompt: Each whole is 1/1.
- Write 9 as a fraction with denominator 4. What is the numerator? → 36Prompt: Each whole is 4/4.
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: Subtract a fraction from a whole number. 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: 3 − 2/5 = ? (Give a mixed number.)
- Step 1: 3 = 2 5/5
- Step 2: 2 3/5
- Answer: 13/5 (2 3/5)
- 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.
- 2 − 1/8 = ? (Give a mixed number.) → 15/8 (1 7/8)Prompt: Take 1 whole from 2 and change it into 8/8.
- Mei has 3 litres of juice and pours out 7/8 of a litre. How much juice is left? → 17/8 (2 1/8)Prompt: Write 3 as 2 and 8/8.
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.
- Daniel has 3 litres of juice and pours out 5/10 of a litre. How much juice is left? → 5/2 (2 1/2)Prompt: Write 3 as 2 and 10/10.
- 3 − 1/3 = ? (Give a mixed number.) → 8/3 (2 2/3)Prompt: Take 1 whole from 3 and change it into 3/3.
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: Whole numbers written as fractions.
- 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: Subtract mixed numbers by regrouping a whole.
- 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