Just to eliminate some confusion. A sample is purposive when you pick a group because they serve a distinct purpose. A reading class for an experiment on, let's say, reading! It needs to have distinct qualities to be a purposive sample. If you interviewed the students in your study hall, you are conducting a convenience sample because you are interviewing them because it is easy to do so and they are no more significant than anyone else.
Keep up the posts, they are fun to read even when they are jabs at me It is the best we can do a creating a class discussion. Glad everyone likes all the powerpoints and podcasts!