Math lesson plan · 6th grade (Year 7 in England) · 30 minutes
Quartiles, IQR and box plots
Statistics and probability
CCSS 6.SP.B.4CCSS 6.SP.B.5.CEngland: GCSE Higher Statistics
Objective and success criteria
Students will: Quartiles, IQR and box plots.
- 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: Mean, median, mode and range
Leads to: the next skill in this area.
Materials: Squared paper for charts, Class survey data, Sticky notes for a live chart, Mini whiteboards and pens, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (Mean, median, mode and range). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Find the mean of: 22, 21, 19, 19, 20, 19, 20 → 20Prompt: Add all the numbers.
- Find the median of: 3, 4, 17, 14, 21, 14, 23, 3 → 14Prompt: Put the numbers in order first.
- Find the range of: 12, 6, 9, 17, 15, 6 → 11Prompt: Range = largest − smallest.
Hook · 3 min
- Take a quick class survey (favorite fruit, travel to school) and ask what the results tell us.
- Share the objective: Quartiles, IQR and box plots. 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: Find the lower quartile (Q1) of: 2, 9, 16, 20, 22, 23, 27, 33, 35, 37, 40
- Step 1: Median = 23
- Step 2: Q1 = 16, Q3 = 35
- Answer: 16
- 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.
- Find the lower quartile (Q1) of: 15, 21, 22, 25, 27, 31, 31, 32, 35, 38, 39 → 22Prompt: The data are in order. Find the median first.
- A box plot shows: minimum 2, Q1 8, median 11, Q3 14, maximum 21. What is the interquartile range? → 6Prompt: Range = maximum − minimum.
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.
- A box plot shows: minimum 5, Q1 8, median 14, Q3 22, maximum 26. What is the range? → 21Prompt: Range = maximum − minimum.
- Find the lower quartile (Q1) of: 1, 1, 6, 15, 23, 31, 37 → 1Prompt: The data are in order. Find the median first.
Watch out for
- Forgetting to put data in order before finding the median.
- Reading a bar's height wrongly when the scale goes up in 2s or 5s.
Support and stretch
Support
- Review first: Mean, median, mode and range.
- Use concrete materials: squared paper for charts.
- 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-6.
Free lesson plan from eurekami.com/lesson-plan-builder