Using Powerpoint when teaching pie charts enable the learners to see exactly what you are doing when you draw a pie chart. In the example I tried to set the powerpoint up exactly as you would do when you draw the graph by hand. This take the pain out of teaching pie charts and enable you to do it in much less time than before.
There is 2 more charts that the learners can then draw by themselves. The second one has an extension part that can lead to a good class discussion about time management.