My best class was a chemistry course taught by a 60 year old man that used to test missiles at one point. The grades never really mattered and as long as you knew the vocabulary he would pass you. But where he made a difference was giving us examples of why stuff worked along with how. For the final we had to determine what an unknown substance was. There was no right method to do this, just simply a number of different tests that we had to do and be able to understand what the results were. We then had to 'think' as to what it might mean about the substance we were testing. He set us free and we passed and failed on our own accord because it was up to the students to read the book to try and find just one more test that might give a better result.
The one lasting comment that my chemistry teacher told me was that he was not concerned with how well we memorized things because he knew we would forget. There would always be time to read up on whatever we were doing on the job. He wanted us to have the core understanding so that when we did look up the boiling point or specific gravity of a compound we would know what those facts would signify as opposed to learning stats on the more common elements. Best teacher I ever had because he didn't so much as teach me as he made me think for myself.