Box Plot Basics Worksheet
Math Lab Data & Statistics
Box Plot Basics
Mastering the Five-Number Summary & Interpreting Spread
Name:
Date:
Per:
Quick Reference: Anatomy of a Box-and-Whisker Plot
Each section contains exactly 25% of the data
Minimum (Lower Extremity) Whisker (25%) Q1 (Lower Quartile) Median (Q2) (50th percentile) Box = Interquartile Range (Middle 50%) Q3 (Upper Quartile) Whisker (25%) Maximum (Upper Extremity)
1 Part 1: Read the Box Plots & Find the Five-Number Summary
Plot A: Math Quiz Scores (Points out of 20) Read each key value directly from the number line below
0 2 4 6 8 10 12 14 16 18 20
Minimum
Q1 (Lower)
Median (Q2)
Q3 (Upper)
Maximum
Range (Max − Min) =
IQR (Q3 − Q1) =
Plot B: Daily Reading Time (Minutes per Day) Scale: increments of 5 minutes
10 15 20 25 30 35 40 45 50 55 60
Minimum
Q1 (Lower)
Median (Q2)
Q3 (Upper)
Maximum
What is the median reading time?
What is the IQR of the reading time?
2 Part 2: Understanding Quartiles & Percentages
1. What percent of the data is always contained inside the box (between Q1 and Q3)?
A 25%
B 50%
C 75%
2. In Plot B above, what percentage of students read for 45 minutes or more?
A 25%
B 50%
C 75%
3. True or False: If one whisker is longer than the other, that whisker contains more data values.
A True
B False (More spread, same %)
Box Plot Basics · Student Worksheet Page 1 of 2
Part 3: Constructing Box Plots
Calculate the five key values, plot the summary points, and draw the plot
Hands-On Practice
4-Step Method:
1 Order data
→
2 Find Median
→
3 Find Q1 & Q3
→
4 Plot 5 dots & connect
1
Guided Problem: Science Quiz Scores
7 students in the study group
Ordered Data Set:
4, 6, 7, 9, 11, 12, 15
1. Minimum
2. Q1 (Lower)
3. Median (Q2)
4. Q3 (Upper)
5. Maximum
Plot Area: Plot 5 dots above the numbers, then draw the box and whiskers
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
2
Independent Problem: Basketball Points Scored
11 seasonal games played
Raw Data (Unordered): Rewrite these values in order from least to greatest
26, 14, 30, 18, 12, 22, 28, 16, 20, 32, 24
Ordered:
Minimum
Q1 (Lower)
Median (Q2)
Q3 (Upper)
Maximum
Plot Area: Scale from 10 to 34 (increments of 2)
10 12 14 16 18 20 22 24 26 28 30 32 34
Calculate the IQR:
What % of games were ≥ 28 pts?
Box Plot Basics · Student Worksheet Page 2 of 2
Box Plot Breakdown Slides
Math Lab Grade 6–8 Statistics
Data Displays
Box Plot Breakdown
Mastering the Five-Number Summary, Quartiles, and Data Distribution
Lesson Focus: Read, Interpret, and Construct Box-and-Whisker Plots
Box Plot Basics · Teacher Slide Deck
Concept Foundation The 5-Number Summary
Anatomy of a Box Plot
Minimum 25% of data Q1 (Lower) Median (Q2) Middle 50% (IQR = Q3 − Q1) Q3 (Upper) 25% of data Maximum
The Rule of 25%
Each of the 4 sections contains exactly one-quarter (25%) of the data.
The Box (IQR)
The box holds the middle 50% of values, showing how spread out the center is.
Worksheet Walkthrough · Page 1 Plot A: Math Quiz Scores
Answers: Reading Plot A
0 2 4 6 8 10 12 14 16 18 20
Minimum 4
Q1 8
Median 14
Q3 16
Maximum 19
Range: Max − Min = 19 − 4 15
IQR: Q3 − Q1 = 16 − 8 8
Worksheet Walkthrough · Page 1 Plot B: Reading Time (Minutes)
Answers: Reading Plot B
10 15 20 25 30 35 40 45 50 55 60
Minimum 15 min
Q1 25 min
Median 35 min
Q3 45 min
Maximum 55 min
Median reading time: 35 minutes
IQR (45 − 25): 20 minutes
Worksheet Walkthrough · Page 1 Part 2: Concept Check
Quartiles & Percentages Answers
Question 1
What percent of data is always inside the box (between Q1 and Q3)?
Answer B 50%
Question 2
In Plot B, what percentage of students read for 45 minutes or more?
Answer A 25% (Q3 to Max)
Question 3
True/False: A longer whisker contains more data values?
Answer B False (More spread!)
Key Takeaway: Whisker length measures spread, not count. Each quarter has 25% regardless of size!
Construction Strategy Step-by-Step Method
How to Construct a Box Plot
1
Order Data
Sort numbers from least to greatest. Never skip values!
2, 4, 7, 8, 11...
2
Find Median
Locate the exact middle number (Q2) dividing data into halves.
Center of all data
3
Find Q1 & Q3
Find the median of the lower half (Q1) and upper half (Q3).