Math lesson plan · 4th grade (Year 5 in England) · 45 minutes
Add and subtract mixed numbers with the same denominator
Fractions
CCSS 4.NF.B.3.CEngland: Y5 Fractions
Objective and success criteria
Students will: Add and subtract mixed numbers with the same denominator.
- 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 like fractions with a total greater than one
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 (Add like fractions with a total greater than one). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Ava runs 5/8 km on Monday and 7/8 km on Tuesday. How far is that altogether? (Write a mixed number.) → 3/2 (1 1/2)Prompt: Add the fractions.
- Arjun runs 4/8 km on Monday and 7/8 km on Tuesday. How far is that altogether? (Write a mixed number.) → 11/8 (1 3/8)Prompt: Add the fractions.
- Ava runs 3/10 km on Monday and 8/10 km on Tuesday. How far is that altogether? (Write a mixed number.) → 11/10 (1 1/10)Prompt: Add the fractions.
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 mixed numbers with the same denominator. 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 2/4 + 2 2/4 = ?
- Step 1: 5 + 2 = 7
- Step 2: 2/4 + 2/4 = 4/4
- Step 3: 8
- Answer: 8
- 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 1/5 + 1 4/5 = ? → 4Prompt: Add the whole numbers, then add the fractions.
- 6 2/3 − 2 1/3 = ? → 13/3 (4 1/3)Prompt: Subtract the whole numbers, then the fractions.
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.
- 3 2/5 + 1 4/5 = ? → 26/5 (5 1/5)Prompt: Add the whole numbers, then add the fractions.
- 7 5/6 − 5 2/6 = ? → 5/2 (2 1/2)Prompt: Subtract the whole numbers, then the fractions.
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 like fractions with a total greater than one.
- 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