Math lesson plan · 7th grade (Year 8 in England) · 45 minutes
Find the percentage change
Decimals and percentages
CCSS 7.RP.A.3England: KS3 NumberEngland: GCSE Foundation Ratio
Objective and success criteria
Students will: Find the percentage change.
- 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: Increase an amount by a percentage; Decrease an amount by a percentage
Leads to: Percent error of an estimate or measurement
Materials: Place value chart with tenths and hundredths, Hundred squares, Number lines, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Increase an amount by a percentage; Decrease an amount by a percentage). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Increase 680 by 50%. → 1020Prompt: Find 50% of 680.
- Decrease 700 by 50%. → 350Prompt: Find 50% of 700.
- A video had 5900 views. Views went up by 15% the next day. How many views did it have then? → 6785Prompt: Increasing by 15% means you end up with 115%.
Hook · 5 min
- Show two prices or race times with decimals and ask which is bigger, then why.
- Share the objective: Find the percentage change. 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: A club's membership rose from 160 to 192. What is the percentage increase?
- Step 1: Increase = 32
- Step 2: 32 ÷ 160 × 100 = 20%
- Answer: 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.
- A club's membership rose from 300 to 390. What is the percentage increase? → 30Prompt: Find the increase first.
- A phone's price dropped from $140 to $112. What is the percentage decrease? → 20Prompt: Find the decrease.
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.
- A club's membership rose from 220 to 286. What is the percentage increase? → 30Prompt: Find the increase first.
- A runner's 5 km time changed from 37 minutes to 41 minutes. What is the percentage increase? Round to 1 decimal place. → 10.8Prompt: Change ÷ original × 100.
Watch out for
- Thinking 0.45 is bigger than 0.5 because 45 is bigger than 5.
- Moving the digits the wrong way when multiplying or dividing by 10.
Support and stretch
Support
- Review first: Increase an amount by a percentage.
- Use concrete materials: place value chart with tenths and hundredths.
- 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: Percent error of an estimate or measurement.
- 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