Even without regulation, there's another aspect to know of: how to use the features of your calculators. If your teacher doesn't know the model, you'll be left

Even without regulation, there's another aspect to know of: how to use the features of your calculators. If your teacher doesn't know the model, you'll be left learning both new class concepts, and new calculator features on your own. It's entirely doable (I always had my casio graph calculator manual with me through the end of high school), but needs more effort.