Cogito
Grade 6 Math · Chapter 9 · Lesson 2
Centre and Spread
One number for the middle, one for the scatter.
10 problems · about 18 minutes · 6.SP.A.2, 6.SP.A.3, 6.SP.B.5
What this lesson teaches
The child computes mean, median, and range and says what each describes.
- The mean shares the total out equally.
- The median is the middle value in order.
- The range measures spread, and an extreme value moves the mean most.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
1 problemReview — What Makes a Question Statistical: Is "How many siblings does each child in the club have?" statistical?
Answer Yes.
Why It anticipates variability.
Warm Up
Straightforward practice. Get the method working first.
4 problemsWhat is the mean of 6, 8, and 13?
Answer 9
Why 9.
Which is pulled further by one very large value?
Answer The mean.
Why The mean is dragged; the median barely moves.
Mean of 2, 4, and 9?
Answer 5
Why 15 ÷ 3.
Median of 1, 5, and 100?
Answer 5
Why The middle one.
Build It Up
The same ideas with more to keep track of.
2 problemsRange of 12, 4, and 20?
Answer 16
Why 20 − 4.
Mean of 10, 10, 10, and 10?
Answer 10
Why No variability at all.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsThe Mean: What is the mean of 4, 6, 8, and 10?
Answer 7
Why 7.
The Median: What is the median of 3, 7, 9, 12, and 15?
Answer 9
Why 9.
The Range: What is the range of 5, 8, 2, and 11?
Answer 9
Why 9.