Math lesson plan · 6th grade (Year 7 in England) · 45 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 · 5 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: 13, 12, 22, 17 → 16Prompt: Add all the numbers.
- Find the median of: 25, 16, 21, 17, 11, 13, 24 → 17Prompt: Put the numbers in order first.
- Find the mode of: 1, 13, 1, 5, 6, 1 → 1Prompt: The mode is the value that appears most often.
Hook · 5 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 · 10 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 · 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 the lower quartile (Q1) of: 1, 2, 2, 4, 4, 15, 15, 17, 22, 26, 30 → 2Prompt: The data are in order. Find the median first.
- A box plot shows: minimum 2, Q1 10, median 16, Q3 18, maximum 22. What is the range? → 20Prompt: Range = maximum − minimum.
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 box plot shows: minimum 8, Q1 15, median 20, Q3 23, maximum 26. What is the range? → 18Prompt: Range = maximum − minimum.
- Find the interquartile range of: 3, 14, 15, 23, 24, 34, 37 → 20Prompt: 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