• 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 6, 7, 10, 13 is 9. Find the mean absolute deviation. → 2.5Prompt: Find how far each value is from the mean (ignore signs).
2. Find the lower quartile (Q1) of: 21, 18, 31, 36, 14, 17, 50, 1, 31, 21, 11 → 14Prompt: Order the data and find the median.
3. Nia's scores: 22, 23, 24, 23. Felix's scores: 20, 26, 23, 23. Both have mean 23. Whose scores are more consistent (smaller MAD)? (Nia / Felix) → NiaPrompt: 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 159 cm and Class B's is 165 cm. Both have a mean absolute deviation of 2 cm. The difference in means is how many MADs? → 3Prompt: Find the difference between the means.
2. Minutes of daily reading. Aisha's group: 16, 17, 28, 24, 29, 11, 15. Noah's group: 22, 21, 32, 29, 31, 16, 21. Using medians, which group typically reads for longer? (Aisha's group / Noah's group / They are the same) → Noah'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. Minutes of daily reading. Nia's group: 18, 17, 15, 18, 25, 28, 29. Sam's group: 27, 25, 24, 26, 35, 37, 38. Using medians, which group typically reads for longer? (Nia's group / Sam's group / They are the same) → Sam's groupPrompt: Order each list and find the middle value.
2. Class A's mean height is 148 cm and Class B's is 154 cm. Both have a mean absolute deviation of 3 cm. The difference in means is how many MADs? → 2Prompt: Find the difference between the means.

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