Hand drawn pie charts are useful for demonstrating the concept to a class.
A pie chart is used to display a set of data in presentations or other places where the details of the data set are not important. Its greatest utility comes when trying to compare different data points as a percentage of a whole. Because of its limited scope, it is seen more in business than technical applications. Most spreadsheet programs today have the ability to produce pie charts, but it is easy to do by hand for small sets of data. This is especially effective when done on a Smartboard in front of the class.
Convert Your Data
1. Convert all of your data points to percentages of the whole data set. For example, four apples, three oranges, two lemons and one lime equals 40 percent apples, 30 percent oranges, 20 percent lemons and 10 percent limes.
2. Convert the percentages into angles. Since a full circle is 360 degrees, multiply this by the percentages to get the angle for each section of the pie. For the apples, 0.4 X 360 = 144 degrees. For the oranges, 0.3 X 360 = 108 degrees. For the lemons, 0.2 X 360 = 72 degrees. For the limes, 0.1 X 360 = 36 degrees.
3. Make sure the angle calculations are correct by adding all the angles. The total should be 360. 144 + 108 + 72 + 36 = 360.
Drawing the Chart
4. Draw a circle on a blank sheet of paper, using the compass. While a compass is not necessary, using one will make the chart much neater and clearer by ensuring the circle is even.
5. Draw a horizontal line, or radius, from the center to the right edge of the circle, using the ruler or straight edge. This will be the first base line.
6. Measure the largest angle in the data with the protractor, starting at the baseline, and mark it on the edge of the circle. Use the ruler to draw another radius to that point. Use this new radius as a base line for your next largest angle and continue this process until you get to the last data point. You will only need to measure the last angle to verify its value since both lines will already be drawn.
7. Label and shade the sections of the pie chart to highlight whatever data is important for your use.