This is my first time out of the franchise loop when it comes to formal instruction. I'm taking lessons from a gentleman who charges $70 for forty-five minutes, and it's worth every penny. Sometimes he goes over the assigned time, not because I ask him to or anything, but because he gets very into the teaching, etc. Is it polite to leave an extra tip? I mean, I know he's an advanced instructor, but I'm just a broke college student and I'm already paying pretty handsomely...please give me some advice. Thanks! :)

Most people do not tip, so don't worry about it! But if you want to, I can't imagine that it wouldn't be appreciated.