I have been working with colleagues to develop advice on how to adapt teaching methods in the face of widespread use of LLMs by students.
The first point I like to make is that the purpose of having students do tasks is to foster their development. That may sound obvious, but many people don't seem to take notice that the products of student activities are worthless in themselves. We don't have students do push-ups in gym class to help the national economy by meeting some push-up quota. The sole reason for them is to promote physical development. The same principle applies to mental tasks. When considering LLM use, we need to be looking at its effects on student development rather than on student output.
So, what is actually new about LLM use? There has always been a risk that students would sometimes submit homework that was actually the work of someone else, but LLMs enable willing students to do it all the time. Teachers can adapt to this by basing evaluation only on work done in class, and by designing homework to emphasize feedback on key points, so that students will get some learning benefit even though a LLM did the work.
Completely following this advice may seem impossible, because some important forms of work done for evaluation require too much time. Teachers use papers and projects to challenge students in a more elaborate way than is possible in class. These can still be used beneficially if a distinction is made between work done for learning and work done for evaluation. While students develop multiple skills while working on these extended tasks, those skills could be evaluated in class by more concise tasks with a narrower focus. For example, good writing requires logical coherence and rhetorical flow. If students have trouble in these areas, it will be just as evident in a brief essay as a long one.