My classmates asked that question and the professor kept on talking about the probability of getting scammed but he's really against the whole crypto-currency movement so his opinion is biased.
So...here I am, asking for guidance...
Is it mandatory for you to enlightened your professor? Don't take that seriously and just let him believed on his thoughts about cryptocurrency. Even how good your explanation, since you said your professor biased, no way he will changed his mind.
About what should we know to avoid risk of getting scammed, honestly we have lots of pointers to that. Mainly, if you are really new into crypto and want to do trading, try to spend time researching to those reputable ones. But that doesn't mean you are safe. We are just minimizing the risks of getting fuck*d up here that's why we need to stick to those big ones. Once you understand the risks, then you may now play with other exchanges.
But before this statement goes long, come back here if you are really serious. Don't want to waste time to those asking questions but will not read entirely all replies here.