• 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 8, 17, 17, 9, 9 is 12. Find the mean absolute deviation. → 4Prompt: Find how far each value is from the mean (ignore signs).
2. Find the upper quartile (Q3) of: 26, 49, 44, 2, 9, 44, 33 → 44Prompt: Order the data and find the median.
3. Lucia's scores: 22, 25, 28, 25. Fatima's scores: 17, 33, 25, 25. Both have mean 25. Whose scores are more consistent (smaller MAD)? (Lucia / Fatima) → LuciaPrompt: 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 167 cm. Both have a mean absolute deviation of 3 cm. The difference in means is how many MADs? → 4Prompt: Find the difference between the means.
2. Minutes of daily reading. Aisha's group: 22, 16, 11, 20, 25, 30, 19. Amara's group: 29, 19, 15, 23, 31, 33, 26. Using medians, which group typically reads for longer? (Aisha's group / Amara's group / They are the same) → Amara'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. Class A's mean height is 146 cm and Class B's is 154 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. Chloe's group: 18, 27, 15, 24, 17, 30, 27. Mei's group: 26, 35, 24, 32, 27, 40, 34. Using medians, which group typically reads for longer? (Chloe's group / Mei's group / They are the same) → Mei'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.