While it is still making noise. It is still functioning. It could fail tomorrow or keep working. Even if it keeps working it won't cool as effectively and the motor can overheat. It can also draw more power to overcome friction.
It is a critical component for cooling your computer. I would urge you to replace it. When it does completely fail. Your computer will overheat. When it overheats it will shutdown to protect itself. But can be irreversibly damaged.
Also, since this is being used in class. The polite thing to do would be to replace it. So, that you aren't disrupting the lecture with a needlessly noisy computer.
Sounds like the cooling fan bearing is shot. If it is still under warranty. Get it replaced. If it isn't you can usually find a replacement fan for your make and model on eBay. There are plenty of videos for opening them up on Youtube.
You may need to reapply thermal paste. If you have to take off the heatsink, you will. This is you chance to also apply it correctly. As factories normally use way too much. So, your laptop may run cooler and quieter.