• 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 22, 25, 23, 19, 11 is 20. Find the mean absolute deviation. → 4Prompt: Find how far each value is from the mean (ignore signs).
2. Find the upper quartile (Q3) of: 5, 4, 2, 40, 31, 47, 8, 20, 2, 25, 20 → 31Prompt: Order the data and find the median.
3. Sam's scores: 22, 23, 24, 23. Diego's scores: 18, 28, 23, 23. Both have mean 23. Whose scores are more consistent (smaller MAD)? (Sam / Diego) → SamPrompt: 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 151 cm and Class B's is 160 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. Isla's group: 10, 14, 16, 25, 12, 16, 23. Liam's group: 16, 22, 20, 32, 18, 21, 29. Using medians, which group typically reads for longer? (Isla's group / Liam's group / They are the same) → Liam'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 6 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. Two basketball players' points per game: Priya has median 18 and IQR 12; Kofi has median 18 and IQR 17. Who is more consistent? (Priya / Kofi) → PriyaPrompt: Consistency is about spread, not the average.
2. Minutes of daily reading. Tariq's group: 28, 27, 20, 21, 22, 14, 13. Maya's group: 39, 38, 29, 29, 29, 24, 22. Using medians, which group typically reads for longer? (Tariq's group / Maya's group / They are the same) → Maya's groupPrompt: Order each list and find the middle value.

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