Feeling hungry?

1. Feeling hungry? Have a slice of pie ;)

2. Pie charts

3. Pie charts….. • Let us see a set of data very easily • Without using numbers • Here’s one now……

6. Every pie chart has… • A title • A key • Sectors These follow….

7. Title

8. A key

9. Sectors

10. More pie charts

14. 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 Now let’s try a real one

15. Constructing a chart Doing the Maths bit…

16. 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 ;)

17. Check out the factors of 360 • On your own or in pairs, work out as many factors of 360 as you can • Answers follow…

18. 1 2 3 4 5 6 8 Factors of 360

19. Factors of 360 • 9 • 10 • 12 • 15 • 18 • 20 • 30

20. Factors of 360 • 36 • 40 • 45 • 60 • 72 • 90 • 120 • 180

21. 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…

22. Working it out…. • Then 1 in 12 prefer tea • 8 out of 12 prefer coffee • 3 out of 12 prefer “other” drinks

23. 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

24. 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 Calculating the angles

25. 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

26. 1 x 360 12 1 1 x 360 = 360 360 divided by 12 = 30 So the sector for tea will be 30 degrees wide Sector size for tea

27. 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

28. 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

29. 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

30. 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°

31. Looks like this…