• 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 13, 16, 14, 15, 22 is 16. Find the mean absolute deviation. → 2.4Prompt: Find how far each value is from the mean (ignore signs).
2. Find the upper quartile (Q3) of: 28, 2, 46, 25, 14, 37, 17, 46, 46, 5, 8 → 46Prompt: Order the data and find the median.
3. Hana's scores: 27, 29, 31, 29. Ravi's scores: 25, 33, 29, 29. Both have mean 29. Whose scores are more consistent (smaller MAD)? (Hana / Ravi) → HanaPrompt: MAD measures how spread out the data is around the mean.

• 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.

• 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.

• 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 152 cm and Class B's is 172 cm. Both have a mean absolute deviation of 5 cm. The difference in means is how many MADs? → 4Prompt: Find the difference between the means.
2. Minutes of daily reading. Yuki's group: 25, 14, 12, 30, 24, 24, 30. Ben's group: 27, 18, 17, 35, 28, 30, 35. Using medians, which group typically reads for longer? (Yuki's group / Ben's group / They are the same) → Ben's groupPrompt: Order each list and find the middle value.

• 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.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. Minutes of daily reading. Diego's group: 25, 30, 18, 24, 22, 18, 20. Ravi's group: 29, 33, 22, 27, 26, 19, 25. Using medians, which group typically reads for longer? (Diego's group / Ravi's group / They are the same) → Ravi's groupPrompt: Order each list and find the middle value.
2. Two basketball players' points per game: Felix has median 18 and IQR 9; Kofi has median 18 and IQR 12. Who is more consistent? (Felix / Kofi) → FelixPrompt: Consistency is about spread, not the average.

Free online practice with hints and printable worksheets for this skill: eurekami.com/math/grade-7.