• 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 9, 11, 13, 6, 6 is 9. 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: 4, 22, 23, 47, 46, 50, 23 → 47Prompt: Order the data and find the median.
3. Isla's scores: 22, 25, 28, 25. Zara's scores: 20, 30, 25, 25. Both have mean 25. Whose scores are more consistent (smaller MAD)? (Isla / Zara) → IslaPrompt: 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 156 cm and Class B's is 160 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. Tariq's group: 23, 29, 14, 14, 30, 28, 15. Arjun's group: 33, 39, 20, 20, 37, 34, 22. Using medians, which group typically reads for longer? (Tariq's group / Arjun's group / They are the same) → Arjun'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. Yuki's group: 15, 12, 27, 14, 18, 16, 30. Kai's group: 21, 16, 31, 20, 24, 21, 33. Using medians, which group typically reads for longer? (Yuki'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: Chloe has median 18 and IQR 6; Yuki has median 18 and IQR 8. Who is more consistent? (Chloe / Yuki) → ChloePrompt: Consistency is about spread, not the average.

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