2.4 Small Group · Group 1
Tier 2 Intervention · Concrete-Representational-Abstract (CRA) · Dual-Language Anchors
Display Data with Box Plots · Box Plot · Procedural Fluency · Real-World Applications
- A box plot is a simple picture that shows how a set of data is spread out, using just five key numbers: the lowest value, the first quartile (Q1), the median (middle), the third quartile (Q3), and the highest value. We'll walk through a worked example, try one together, then you'll try a few with hints right there when you need them.
- 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.
- 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 MULTIPLE CHOICE
On a box plot, what does the line inside the box represent?
- AThe median
- BThe mean
- CThe mode
- DThe range
✏️ Workspace & Solution Steps -
2 DRAG SORT
Order the steps for making a box plot.
- Step 1: Order the data from least to greatest
- Step 2: Find the median (middle value)
- Step 3: Find Q1 (median of the lower half)
- Step 4: Find Q3 (median of the upper half)
- Step 5: Draw the box from Q1 to Q3 with a line at the median, and whiskers to min and max
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3 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
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4 MULTIPLE CHOICE
A box plot shows: Min = 10, Q1 = 15, Median = 20, Q3 = 28, Max = 35. What is the interquartile range (IQR)?
- A13
- B25
- C10
- D20
Put the data in orderWork- 1OrderSmallest to largest.
- 2CountHow many values?
- 3LocateMiddle, or add and divide.
- 4AnswerSay which measure it is.
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5 MULTIPLE CHOICE
What percentage of data falls between Q1 and Q3 on a box plot?
- A50%
- B25%
- C75%
- D100%
Put the data in orderWork- 1OrderSmallest to largest.
- 2CountHow many values?
- 3LocateMiddle, or add and divide.
- 4AnswerSay which measure it is.
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6 MULTIPLE CHOICE
Find the range of: 14, 22, 8, 31, 17
- A23
- B31
- C8
- D18
Put the data in orderWork- 1OrderSmallest to largest.
- 2CountHow many values?
- 3LocateMiddle, or add and divide.
- 4AnswerSay which measure it is.
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.