There is a lot of coaching opportunity here for both the project manager and the intern. For example, we might talk about clear communication throughout the project, and the importance of creating check-in points to assess progress against the goal. It might be important in this case for both the manager and the intern to have been proactive in making sure expectations and needs were being met, perhaps after 4 hours of work, or after an initial milestone was completed. But even with all that, if you're an intern or a new hire, I'd like to make the case for doing additional work, even if it's beyond what you expected and even what you were paid for.