Back to the lesson plan builder
Lesson length30 min45 min60 min
Questions🔀 New questions

Print the plan for yourself; the student sheet prints on its own page after it.

Math lesson plan · 7th grade (Year 8 in England) · 45 minutes

Compare two groups using centre and spread

Statistics and probability

CCSS 7.SP.B.3CCSS 7.SP.B.4England: KS3 StatisticsEngland: GCSE Foundation Statistics

Objective and success criteria

Students will: Compare two groups using centre and spread.

  • 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 absolute deviation (MAD); Find quartiles and the interquartile 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 absolute deviation (MAD); Find quartiles and the interquartile range). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. The mean of 18, 14, 17, 7 is 14. Find the mean absolute deviation. → 3.5Prompt: Find how far each value is from the mean (ignore signs).
  2. Find the lower quartile (Q1) of: 5, 46, 40, 45, 48, 43, 18, 40, 21, 5, 10 → 10Prompt: Order the data and find the median.
  3. Ben's scores: 21, 23, 25, 23. Kwame's scores: 16, 30, 23, 23. Both have mean 23. Whose scores are more consistent (smaller MAD)? (Ben / Kwame) → BenPrompt: MAD measures how spread out the data is around the mean.

Hook · 5 min

  • Take a quick class survey (favorite fruit, travel to school) and ask what the results tell us.
  • Share the objective: Compare two groups using centre and spread. 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: Class A's mean height is 145 cm and Class B's is 157 cm. Both have a mean absolute deviation of 3 cm. The difference in means is how many MADs?
  • Step 1: 157 − 145 = 12
  • Step 2: 12 ÷ 3 = 4
  • Answer: 4
  • 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.
  1. Class A's mean height is 140 cm and Class B's is 144 cm. Both have a mean absolute deviation of 2 cm. The difference in means is how many MADs? → 2Prompt: Find the difference between the means.
  2. Minutes of daily reading. Ines's group: 10, 25, 23, 15, 24, 15, 15. Hiro's group: 17, 29, 27, 19, 28, 20, 20. Using medians, which group typically reads for longer? (Ines's group / Hiro's group / They are the same) → Hiro's groupPrompt: Order each list and find the middle value.

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.
  1. Minutes of daily reading. Kofi's group: 15, 11, 16, 12, 28, 16, 27. Kai's group: 24, 22, 25, 19, 35, 26, 36. Using medians, which group typically reads for longer? (Kofi's group / Kai's group / They are the same) → Kai's groupPrompt: Order each list and find the middle value.
  2. Two basketball players' points per game: Kofi has median 18 and IQR 4; Luis has median 18 and IQR 6. Who is more consistent? (Kofi / Luis) → KofiPrompt: Consistency is about spread, not the average.

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 absolute deviation (MAD).
  • 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-7.

Free lesson plan from eurekami.com/lesson-plan-builder

eurekami

Compare two groups using centre and spread

Name

Date

Score/ 8

  1. Question 1

    Class A's mean height is 141 cm and Class B's is 147 cm. Both have a mean absolute deviation of 3 cm. The difference in means is how many MADs?

    Answer

  2. Question 2

    Minutes of daily reading. Maya's group: 17, 28, 12, 18, 16, 19, 15. Mateo's group: 28, 38, 19, 26, 25, 28, 25. Using medians, which group typically reads for longer?

    • A. Maya's group
    • B. Mateo's group
    • C. They are the same

  3. Question 3

    Two basketball players' points per game: Liam has median 18 and IQR 7; Arjun has median 18 and IQR 4. Who is more consistent?

    • A. Liam
    • B. Arjun

  4. Question 4

    Class A's mean height is 148 cm and Class B's is 160 cm. Both have a mean absolute deviation of 4 cm. The difference in means is how many MADs?

    Answer

  5. Question 5

    Minutes of daily reading. Arjun's group: 12, 18, 23, 18, 22, 11, 16. Yuki's group: 18, 20, 28, 20, 25, 17, 21. Using medians, which group typically reads for longer?

    • A. Arjun's group
    • B. Yuki's group
    • C. They are the same

  6. Question 6

    Two basketball players' points per game: Maya has median 18 and IQR 9; Hana has median 18 and IQR 14. Who is more consistent?

    • A. Maya
    • B. Hana

  7. Question 7

    Class A's mean height is 159 cm and Class B's is 171 cm. Both have a mean absolute deviation of 3 cm. The difference in means is how many MADs?

    Answer

  8. Question 8

    Minutes of daily reading. Noah's group: 20, 11, 17, 27, 23, 24, 14. Amara's group: 29, 18, 26, 38, 33, 31, 25. Using medians, which group typically reads for longer?

    • A. Noah's group
    • B. Amara's group
    • C. They are the same

Free from eurekami.com

for the adult only

Answer key: Compare two groups using centre and spread

  1. 1. 2

  2. 2. B. Mateo's group

  3. 3. B. Arjun

  4. 4. 3

  5. 5. B. Yuki's group

  6. 6. A. Maya

  7. 7. 4

  8. 8. B. Amara's group