Math lesson plan · 6th grade (Year 7 in England) · 45 minutes
Find 50%, 25%, 10%, 5% and 1% mentally
Decimals and percentages
CCSS 6.RP.A.3.CEngland: KS3 NumberEngland: GCSE Foundation Number
Objective and success criteria
Students will: Find 50%, 25%, 10%, 5% and 1% mentally.
- 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: Percentage of an amount
Leads to: Find the whole when you know a percentage of it
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 (Percentage of an amount). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- What is 75% of 20? → 15Prompt: Find 10% (or 1%) first, then build up.
- Find 35% of 540. → 189Prompt: 10% of 540 is 54. What are 5% and 1%?
- There are 420 students at an event. 40% of them arrive by bike. How many arrive by bike? → 168Prompt: Find 40% of 420.
Hook · 5 min
- Show two prices or race times with decimals and ask which is bigger, then why.
- Share the objective: Find 50%, 25%, 10%, 5% and 1% mentally. 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: Find 50% of 300 in your head.
- Step 1: 50% of 300 = 150
- Answer: 150
- 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.
- Find 5% of 380 in your head. → 19Prompt: For 5%: find 10%, then halve it.
- Find 55% of 800 by building it from 10% and 5%. → 440Prompt: 10% of 800 is 80.
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.
- Ravi says: “15% of 540 is 10% of 540 plus 5, so it is 59.” What is 15% of 540 really? → 81Prompt: 5% is not the number 5: it is half of 10%.
- Find 20% of 120 in your head. → 24Prompt: For 20%: find 10%, then double it.
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: Percentage of an amount.
- 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: Find the whole when you know a percentage of it.
- 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-6.
Free lesson plan from eurekami.com/lesson-plan-builder