Open University: could do better...

I went to a tutorial last Tuesday hopping to understand better the distribution of molecular speed. Well, I'm still in the dark as how the boltzmann constant has been derived. I know, I'm only supposed to use the formula in the book, but I hate learning off by heard stuff without understanding them.
My tutor is nice, but didnt seem to be at ease with this subject. And more and more, I have the impression that going to tutorial is just a waste of time. The positive thing is that the tutor gave us a little summing up of the first chapter of the book "classical physics of matter". He told us that the exam question on this topic is going to be basic and that we shouldnt worry too much about understanding the derivation and more focussing on how to use the formula.
Well, I dont do this course only to have a degree in Physics, but also because I LOVE physics. So learning off by heart stuff that I dont really understand, is not my prefered option. The tutor suggested I buy one book devoted excusively to mechanics statistics. Yes, well... sure. Maybe another time.