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