6th grade · Math · Unit 17 of 19
Center & Spread
Mean, median, range and IQR
What your child practices
Telling a statistical question from a regular question, and describing data with the mean, median, range and interquartile range.
Texas Essential Knowledge and Skills (TEKS) teks student expectation: 6.12(C); 6.13(B) · mean, median, range and interquartile range, and data with and without variability
How we explain it
Children can open this short lesson before they practice.
- Mean: add the values and divide by how many there are.
- Median: the middle value in order. Range: greatest − least.
- IQR: Q3 − Q1, the spread of the middle half.
Example: What is the mean of 4, 7, 9 and 12? 4 + 7 + 9 + 12 = 32. 32 ÷ 4 = 8. Answer: 8
Center & Spread in Texas
In the Texas Essential Knowledge and Skills (TEKS), this is unit 17 of 19 in 6th grade Math, after Data & Graphs and before Adding & Subtracting Integers.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Source: Texas Education Agency (TEA)
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
What is the median of 17, 4, 8, 19, 13?
- 8
- 12
- 13
- 14
- 13.5
13
Hint: Put the numbers in order. The median is the middle one (or the mean of the two middle ones).
Question 2
What is the interquartile range (IQR) of 8, 1, 8, 12, 21, 19, 38, 15?
- 14
- 37
- 8
- 20
- 12
12
Hint: Order the data. Q1 = 8 (middle of the lower half), Q3 = 20 (middle of the upper half). IQR = Q3 − Q1.
Question 3
The data 12, 13, 13, 15, 20, 82 has one very large value. Which measure describes the typical value best?
- The median
- The mean
- The range
The median
Hint: One extreme value pulls the mean and range a long way, but the median barely moves.
Question 4
What is the mean of 3, 13, 13, 4, 12?
- 7
- 6
- 10
- 9
- 12
9
Hint: Add them (45) and divide by 5.
Question 5
Which is a statistical question?
- How tall is the school flagpole?
- How many hours did I sleep last night?
- How long are the songs on my favorite playlist?
- How many days are in a leap year?
How long are the songs on my favorite playlist?
Hint: A statistical question expects answers that vary, so you collect data to answer it.
Question 6
What is the range of 24, 31, 54, 33, 21, 60?
- 39
- 60
- 32
- 41
- 40
39
Hint: Range = greatest − least.