This is simple logic. Where is the clause or amendment in the Constitution clearly and specifically authorizing the formation of a national or central bank? If it's there, I can't find it, and neither can your so-called teacher.
As the 10th amendment clearly states, anything not explicitly called out in the document, is something reserved to (the exclusive domain of) the states.
Anything else not explicitly called out is subject to interpretation, unfortunately, by the Supreme Court. In any case, to my knowledge, the Constitutionality of the Fed has never been challenged and upheld in that venue - but I could be wrong.
And last - who would want to live in a country that allows it's government to systematically devalue its' currency and arbitrarilty set the price of money? At root, that's legalized theft.