Feeling hungry?
Have a slice of pie ;)
Pie charts
Pie charts…..
• Let us see a set of data very easily
• Without using numbers
• Here’s one now……
Drinking preferences of
Numeracy students
Tea
Coffee
Neither
Drinking preferences of
Numeracy students
Tea
Coffee
Neither
Every pie chart has…
• A title
• A key
• Sectors
These follow….
Title
Drinking preferences of
Numeracy students
Tea
Coffee
Neither
Drinking preferences of
Numeracy students
Tea
Coffee
Neither
A key
Drinking preferences of
Numeracy students
Tea
Coffee
Neither
Sectors
More pie charts
Numbers of people who follow pie
charts in Dave's class
People who
understand pie
charts
People who don’t
understand pie
charts
How well do Dave's students
understand pie charts?
People who
understand pie
charts
People who don’t
understand pie
charts
People who can't
be bothered with
charts
Student understanding of pie charts
Understand pie
charts
Don’t understand
pie charts
Can't be
bothered
Missing from
session
Now let’s try a real one
• Do a survey of the
group and whether
people prefer tea,
coffee or neither,
using the tally method
• Let’s see what that
looks like as a pie
chart
•
End E3 here
Constructing a chart
Doing the Maths bit…
Back to the Babylonians
• They divided a circle into 360 degrees
• This matched the number of days in a year
very closely
• It is also a number with many factors, so it
is easy to divide down and calculate with,
without getting into fractions ;)
Check out the factors of 360
• On your own or in pairs, work out as many
factors of 360 as you can
• Answers follow…
Factors of 360
•
•
•
•
•
•
•
1
2
3
4
5
6
8
Factors of 360
•
•
•
•
•
•
•
9
10
12
15
18
20
30
Factors of 360
•
•
•
•
•
•
•
•
36
40
45
60
72
90
120
180
Working out the angles…
• Let’s imagine we do a survey of 12 people
to find out whether they prefer tea, coffee,
or some other drink
• Let’s say there is 1 who prefers tea, 8
coffee and 3 some other drink…
Working it out….
• Then 1 in 12 prefer tea
• 8 out of 12 prefer coffee
• 3 out of 12 prefer “other” drinks
Changing the English to Maths
• 1 in 12 for tea = 1/12
• 8 out of 12 for coffee = 8/12
• 3 out of 12 for “other” = 3/12
Calculating the angles
• 1 tea out of 12
• Tea sector = 1/12 x
360
• 8 coffee out of 12
• Coffee = 8/12 x 360
• 3 “other” out of 12
• “Other” = 3/12 x 360
Do the Maths….for tea
•
1
x
360
12
You can put any number over 1 - this
doesn’t change its value, and lets you
multiply it as a fraction
•
1
12
x
360
1
Sector size for tea
• 1
12
x
360
1
• 1 x 360 = 360
• 360 divided by 12 =
30
• So the sector for tea
will be 30 degrees
wide
Do the Maths….for coffee
•
8
x
360
12
You can put any number over 1 - this
doesn’t change its value, and lets you
multiply it as a fraction
•
8
12
x
360
1
Sector size for coffee
• 8
12
x
360
1
• Reduce 8/12 to its
lowest terms – 2/3
• 2
3
x
360
1
• Either do 360 x 2 and
divide by 3
• Or divide the 360 first
by 3 then double it
• = 240 degrees
Boxing clever
• Some people always work out the basic
sector first and then multiply up from that
• We know 1/12 prefer tea = 30 degrees
• Coffee is 8/12 – so that will be 8 x 30!
• Now let’s see the “other” category
Sector size for “other”
• 3/12 prefer “other”
• We know 1/12 = 30 degrees
• So 3/12 will be 90 degrees (90°)
• Also, 3/12 = ¼ , and a quarter of a circle is
90°
Looks like this…
Who likes what to drink?
Tea
Coffee
Other