• 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 15, 11, 10, 13, 21 is 14. Find the mean absolute deviation. → 3.2Prompt: Find how far each value is from the mean (ignore signs).
2. Find the lower quartile (Q1) of: 36, 21, 41, 27, 1, 3, 3 → 3Prompt: Order the data and find the median.
3. Grace's scores: 14, 17, 20, 17. Priya's scores: 11, 23, 17, 17. Both have mean 17. Whose scores are more consistent (smaller MAD)? (Grace / Priya) → GracePrompt: 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 155 cm and Class B's is 163 cm. Both have a mean absolute deviation of 2 cm. The difference in means is how many MADs? → 4Prompt: Find the difference between the means.
2. Minutes of daily reading. Yuki's group: 23, 15, 23, 14, 11, 15, 21. Lucia's group: 33, 25, 33, 24, 17, 23, 27. Using medians, which group typically reads for longer? (Yuki's group / Lucia's group / They are the same) → Lucia'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. Class A's mean height is 153 cm and Class B's is 165 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.
2. Two basketball players' points per game: Ava has median 18 and IQR 12; Lucia has median 18 and IQR 9. Who is more consistent? (Ava / Lucia) → LuciaPrompt: Consistency is about spread, not the average.

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