2.4 Small Group · Group 2
Tier 1 Extension · Non-Routine Synthesis · Misconception Traps · Rigorous CER Proofs
Display Data with Box Plots · Box Plot · Procedural Fluency · Real-World Applications
- You already can do this. So we go up a level, not up a number: find what is always true, show it a second way, and be ready to defend it with a reason instead of an answer.
- My data, in order: 4, 6, 8, 10, 12, 14, 15, 18, 22, 24, 28. There are 11 numbers.
- The middle number is the 6th one, 14, so the median = 14.
- The lower half is 4, 6, 8, 10, 12. Its middle is 8, so Q1 = 8.
- The upper half is 15, 18, 22, 24, 28. Its middle is 22, so Q3 = 22.
- The lowest is 4 and the highest is 28. I draw a box from 8 to 22, a line at 14, and whiskers out to 4 and 28.
- New, smaller data set: 2, 5, 5, 8, 11. First, what is the median (the middle value)?
- The lower half is 2, 5 and the upper half is 8, 11. What is Q1? What is Q3?
- What are the lowest and highest values? Now picture the box stretching from Q1 to Q3 with the median line inside.
- Now prove it: say why that move had to work at all — not just that it did.
- Sentence frame — convince a skeptic: "My method works because ___ . It would stop working if ___ ."
- Display Data with Box Plots (Representar datos con diagramas de caja) — Show a data set's five-number summary in a box-and-whisker display.
- Box Plot (Diagrama de caja) — A graph that shows how data is spread using five key numbers.
- Median (Mediana) — The middle number when you put them in order.
- Quartile (Cuartil) — Numbers that split the data into four equal parts.
- Interquartile Range (Rango intercuartílico) — The spread of the middle half of the data (Q3 − Q1).
- Data distribution (Distribución de datos) — How the data looks: where it sits and how spread out it is.
- A common mistake in Display Data: Box Plots is treating a quartile as just one data point instead of the median of a half — for the lower half 4, 8, 10, 14, some students pick 10 (the last value) as Q1 instead of finding the median of that half: Q1 = (8 + 10) ÷ 2 = 9. A second common slip is finding IQR by adding the quartiles instead of subtracting, writing IQR = Q3 + Q1 (like 30 + 18 = 48) instead of IQR = Q3 − Q1 (30 − 18 = 12) — always order the data first, then subtract Q1 from Q3 to find the spread of the middle 50%.
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1 FILL TABLE
Solve the mathematical problem. Show all of your work and reasoning.
Measure Value Data: 5, 8, 12, 15, 18, 20, 25, 30, 35 Minimum Q1 (median of lower half: 5, 8, 12, 15) Median Q3 (median of upper half: 20, 25, 30, 35) Maximum IQR (Q3 − Q1) ✏️ Scratchpad / Reasoning -
2 MATCHING GAME
Match each box plot term to its meaning.
- Minimum
- Q1
- Median
- Q3
- IQR
- Maximum
- ASmallest value in the data set
- BMedian of the lower half
- CMiddle value of the entire data set
- DMedian of the upper half
- EQ3 − Q1 (spread of middle 50%)
- FLargest value in the data set
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3 MULTIPLE CHOICE
The Hawks' points per quarter are 2, 4, 5, 7, 8, 10, 12. Resting on the scoreboard, what are the minimum, median, and maximum?
- AMinimum 2, median 7, maximum 12
- BMinimum 2, median 5, maximum 12
- CMinimum 0, median 7, maximum 12
- DMinimum 2, median 8, maximum 10
✏️ Workspace & Solution Steps -
4 MULTIPLE CHOICE
The Comets scored 6, 10, 14, 18, 22, 26, 30, 34 across 8 games. After ordering, what are Q1 and Q3?
- AQ1 = 12, Q3 = 28
- BQ1 = 10, Q3 = 30
- CQ1 = 14, Q3 = 26
- DQ1 = 20, Q3 = 34
✏️ Workspace & Solution Steps -
5 MULTIPLE CHOICE
A box plot for the Rockets shows Min = 8, Q1 = 15, Median = 22, Q3 = 30, Max = 38. The middle 50% of their scores falls between which two values?
- ABetween 15 and 30
- BBetween 8 and 38
- CBetween 8 and 22
- DBetween 22 and 38
✏️ Workspace & Solution Steps
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6 ERROR ANALYSIS
Level 2 Extension — The Skipped Ordering Mistake
- 1Data (as recorded):Falcons' scores: 17, 5, 21, 9, 29, 13, 25
- 2Minimum and maximum:Min = 5, Max = 29 ✓
- 3Median:The middle value of the list is 9, so Median = 9
- 4Q1 and Q3:Lower half = 17, 5, 21 → Q1 = 5. Upper half = 13, 25 → Q3 = 25
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation
Group Discussion Prompt: How does your visual model justify your mathematical solution?
Partner A: "I modeled this by identifying the relationship and..."
Partner B: "I agree with your step because the standard mathematical rule states..."
Complete each sentence stem to demonstrate precise mathematical reasoning:
Writing Task: Justify why your mathematical solution is accurate and complete.