Math lesson plan · 7th grade (Year 8 in England) · 30 minutes
Add and subtract negative fractions
Number sense
CCSS 7.NS.A.1.DEngland: KS3 Number
Objective and success criteria
Students will: Add and subtract negative fractions.
- 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: Subtract integers by adding the opposite; Add and subtract fractions with unlike denominators
Leads to: the next skill in this area.
Materials: Place value chart, Base-ten blocks or a number line, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (Subtract integers by adding the opposite; 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 − (−9) = ? → 12Prompt: Subtracting a negative is the same as adding a positive.
- 5/6 + 7/12 = ? Give your answer in simplest form. → 17/12 (1 5/12)Prompt: You need a common denominator first.
- −3 − 32 = ? → -35Prompt: Rewrite as −3 + (−32).
Hook · 3 min
- Show a number in the news or a price tag and ask what each digit is worth.
- Share the objective: Add and subtract negative fractions. 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: Work out −8/11 + 7/11. Give a fraction in simplest form (or a whole number).
- Step 1: −8/11 + 7/11 = −1/11
- Answer: -1/11
- 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.
- Work out −2/5 + 4/5. Give a fraction in simplest form (or a whole number). → 2/5Prompt: The denominators match, so add the numerators.
- Work out −1/5 − (−2/3). Give a fraction in simplest form (or a whole number). → 7/15Prompt: Use a common denominator: 15.
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.
- Work out −1 2/3 + 2 1/6. Give a fraction or mixed number in simplest form. → 1/2Prompt: Change both to improper fractions.
- Work out −2/3 − (1/4). Give a fraction in simplest form (or a whole number). → -11/12Prompt: Use a common denominator: 12.
Watch out for
- Reading 1,045 as one thousand four hundred five: point to each place and say its value.
- Thinking a longer number is always bigger, even with decimals (0.45 vs 0.5).
Support and stretch
Support
- Review first: Subtract integers by adding the opposite.
- Use concrete materials: place value chart.
- 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-7.
Free lesson plan from eurekami.com/lesson-plan-builder