The document discusses how to draw and calculate percentages for a pie chart. It provides an example of survey data about which day students would paint scenery for a school play. The data is used to calculate the angles for each sector of the pie chart based on the total of 360 degrees. Students are then asked to draw the pie chart, include a key, and calculate the percentage for each sector. Peer assessment is also discussed to check work for points and stars.

1. PIE CHARTS Calculating angles and percentages

2. Materials needed Classwork book (to copy notes) Protractor Pair of compasses Pencil Ruler Eraser

3. Lesson Objective To be able to draw a pie chart by calculating the degrees for each sector from a set of given data To be able to calculate the percentage for each sector from a set of given data

4. Why Pie charts? A pie chart is a good way of displaying data when you want to show how something is shared or divided.

5. How do we calculate angles? Twenty students were asked on which day they would paint the scenery for the school play. The replies were: Monday - 5 Tuesday - 4 Wednesday - 8 Thursday 3

6. Remember!!! The angles at the centre of a pie chart MUST add up to 360º

7. Calculation 20 students are represented by 360º One student is represented by 360º = 18º 20 Thursday = 3 x 18º = 54º Wednesday = 8 x 18º = 144º Tuesday = 4 x 18º = 72º Monday = 5 x 18º = 90º

8. Now…. Draw the pie chart representing the students Show the key and angle of each sector. Then, calculate the percentage of each parts.

9. Peer Assessment Ask your friends to check your workings: Circle (1 point) Correct angles and sector (4 points) Key shown for days (1 point) Percentage shown (4 points) Total up the number of points (max=10) 8 - 10 points = 3 stars 5 - 7 points = 2 stars 2 - 4 points = 1 star

10. Well Done!!! How well did you do in this exercise? How many stars did you get? Anyone got 3 stars?

11. Reminder!!! Next lesson bring your Classwork book. Email the progress of your survey project to Cikgu Norliza at [email_address] Or post your project in the Facebook web page - Maths Ideas in SMPW, KB Before Thursday, 10 Feb 2011