The longer story
A blanket ban is difficult to enforce and misses the chance to teach judgement, while unrestricted use hollows out the tasks that build skill. Most schools settle somewhere in between by being explicit at the level of the task rather than the subject. Some assignments are AI-free because the struggle is the learning, and those are best assessed in conditions you control. Others invite AI use openly, with students asked to show the prompts they used and what they changed afterwards. Saying which of the two applies, in writing, at the moment the work is set, removes most of the ambiguity that leads to disputes later on.