I ran into a similar issue when I started working professionally. I had a Supervisor who would take smoke breaks and work with me a couple of hours a day for training. I went to my HR person and asked for suggestions on how to best handle since it can easily be taken the wrong way. You're telling someone they smell which can be seen as rude and which was my biggest fear. I needed this person to train me so I would be successful at my job but the smell was distracting and at times, nauseating. The HR person suggested I bring this up in a private setting with my Supervisor so not to embarrass her or possibly write a note anonymously. I went for the former as it felt more appropriate and respectful.
We stepped in a conference room and I explained how difficult it was to broach the subject, how much I appreciated the training and that I didn't mean to offend... but that the smell of cigarettes is causing difficulty for me and I'm apparently very sensitive to it . I apologized but said that I need to be honest since we have a working relationship and just as I appreciate when she was honest with me about my style, technique, ability, whatever, I felt I owed it to her to be honest. She was embarrassed but appreciated it and understood it was about the work. It got better immediately and there were some lapses but we would schedule work time before she went for a cigarette break and she would chew gum to try and help the smell. When the lapses happened she became more aware on the impact to my training and the work
It is not at all wrong to ask. You and your classmates are interested in learning and deserve the best opportunity. It just needs to be done carefully and honestly. I have a feeling your teacher will appreciate it in the long run.
I hope that helps. Let me know how it goes.
All the best - Jonathan