Cogito
Grade 6 Math · Chapter 9 · Lesson 3
Dot Plots and Histograms
Two ways to show the same data.
10 problems · about 18 minutes · 6.SP.B.4
What this lesson teaches
The child builds and reads dot plots and histograms, and says which suits a data set.
- A dot plot shows one dot per value, stacked when values repeat.
- A histogram groups values into bins and shows how many fell in each.
- Binning makes a big data set readable, but hides the individual values.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Centre and Spread: What is the mean of 6, 8, and 13?
Answer 9
Why 9.
Review — What Makes a Question Statistical: Is "How many siblings does each child in the club have?" statistical?
Answer Yes.
Why It anticipates variability.
Review — Finding a Missing Edge: Volume 72, length 6, width 3. Height?
Answer 4
Why 4.
Warm Up
Straightforward practice. Get the method working first.
3 problemsBars of 2, 5 and 6. How many values in all?
Answer 13
Why 13.
Bars of 3, 7 and 4. How many values in all?
Answer 14
Why Add the bars.
In bins of ten, which bin does 25 fall into? Give the lowest value.
Answer 20
Why 20 to 29.
Build It Up
The same ideas with more to keep track of.
2 problemsCan you read an individual value off a histogram?
Answer No. Binning hides them.
Why A bar says how many, not which.
Which suits 200 values spread from 0 to 100?
Answer A histogram.
Why Two hundred dots would be unreadable.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Bin: In bins of ten, which bin does 14 fall into? Give the lowest value of that bin.
Answer 10
Why The 10 to 19 bin.
The Repeat: On a dot plot, three children scored 8. How tall is the stack above 8?
Answer 3
Why 3 dots.