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….
Drinking preferences of Numeracy students
Tea
Coffee
Neither
Title
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 whounderstand piecharts
People who don’tunderstand piecharts
How well do Dave's students understand pie charts?
People whounderstand piecharts
People who don’tunderstand piecharts
People who can'tbe bothered withcharts
Student understanding of pie charts
Understand piecharts
Don’t understandpie charts
Can't bebothered
Missing fromsession
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
• 8 coffee out of 12
• 3 “other” out of 12
• Tea sector = 1/12 x 360
• Coffee = 8/12 x 360
• “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 x 360
12 1
Sector size for tea
• 1 x 360
12 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 x 360
12 1
Sector size for coffee
• 8 x 360
12 1
• 2 x 360
3 1
• Reduce 8/12 to its lowest terms – 2/3
• 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?
TeaCoffee Other