In some instances, it makes sense for community-based learning to be a mandatory part of the curriculum. All of your students should be able to attend a field trip that takes place during normal class hours. But some activities might not be available when the class meets (e.g., evening classes and a day site visit), or you may not have enough placements for everyone in the class. In such cases, you might ask students to write an essay applying for an internship. This generally limits your choices to students who have the time and motivation to complete extra work outside of class. The internship could then be substituted for a paper, project, or presentation.
When offering extra credit for internships, the result may be that students focus more on the internship than on required projects, leading to incomplete work. Yet this on-the-job learning may be the most effective type of learning experience for some students who are not fully engaged in classroom learning. Deciding who can participate might require consideration of any one or a combination of these variables.