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) · 60 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 · 6 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 10, 4, 11, 11 is 9. Find the mean absolute deviation. → 2.5Prompt: Find how far each value is from the mean (ignore signs).
  2. Find the lower quartile (Q1) of: 19, 3, 42, 43, 17, 26, 17 → 17Prompt: Order the data and find the median.
  3. Mateo's scores: 28, 30, 32, 30. Ana's scores: 23, 37, 30, 30. Both have mean 30. Whose scores are more consistent (smaller MAD)? (Mateo / Ana) → MateoPrompt: MAD measures how spread out the data is around the mean.

Hook · 6 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 · 12 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 · 12 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 144 cm and Class B's is 153 cm. Both have a mean absolute deviation of 3 cm. The difference in means is how many MADs? → 3Prompt: Find the difference between the means.
  2. Minutes of daily reading. Ethan's group: 25, 10, 21, 12, 13, 26, 16. Zara's group: 29, 13, 27, 17, 18, 33, 23. Using medians, which group typically reads for longer? (Ethan's group / Zara's group / They are the same) → Zara's groupPrompt: Order each list and find the middle value.

You do: independent practice · 17 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 · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Two basketball players' points per game: Ravi has median 18 and IQR 5; Kwame has median 18 and IQR 7. Who is more consistent? (Ravi / Kwame) → RaviPrompt: Consistency is about spread, not the average.
  2. Class A's mean height is 160 cm and Class B's is 172 cm. Both have a mean absolute deviation of 4 cm. The difference in means is how many MADs? → 3Prompt: Find the difference between the means.

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 147 cm and Class B's is 153 cm. Both have a mean absolute deviation of 2 cm. The difference in means is how many MADs?

    Answer

  2. Question 2

    Two basketball players' points per game: Amara has median 18 and IQR 5; Ana has median 18 and IQR 2. Who is more consistent?

    • A. Amara
    • B. Ana

  3. Question 3

    Minutes of daily reading. Kai's group: 30, 20, 16, 20, 12, 14, 11. Priya's group: 36, 25, 22, 26, 18, 19, 13. Using medians, which group typically reads for longer?

    • A. Kai's group
    • B. Priya's group
    • C. They are the same

  4. Question 4

    Class A's mean height is 145 cm and Class B's is 154 cm. Both have a mean absolute deviation of 3 cm. The difference in means is how many MADs?

    Answer

  5. Question 5

    Two basketball players' points per game: Ethan has median 18 and IQR 10; Maya has median 18 and IQR 12. Who is more consistent?

    • A. Ethan
    • B. Maya

  6. Question 6

    Minutes of daily reading. Omar's group: 15, 11, 30, 28, 20, 13, 22. Yuki's group: 19, 14, 34, 33, 22, 15, 27. Using medians, which group typically reads for longer?

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

  7. Question 7

    Class A's mean height is 141 cm and Class B's is 149 cm. Both have a mean absolute deviation of 4 cm. The difference in means is how many MADs?

    Answer

  8. Question 8

    Two basketball players' points per game: Ines has median 18 and IQR 8; Aisha has median 18 and IQR 11. Who is more consistent?

    • A. Ines
    • B. Aisha

Free from eurekami.com

for the adult only

Answer key: Compare two groups using centre and spread

  1. 1. 3

  2. 2. B. Ana

  3. 3. B. Priya's group

  4. 4. 3

  5. 5. A. Ethan

  6. 6. B. Yuki's group

  7. 7. 2

  8. 8. A. Ines