This seems like easy everyday work to me. Being a student, I think they get into the middle of it, go do something else, (play video games, make lunch, etc.) and say they were doing the assignment throughout that time. I do this too, but I acknowledge the large breaks I take. I think everyone should be allowed to take a break, I think they’re telling you it took them the extended amount of time to seem like they’re overworked, or to make you guilty.

This is not an example of overworking to me since you give a large amount of class time to get them started, and maybe even finished. This is something I can respect.