I frequently comment that physicists don't have to remember but a few fundamental formulae because they can derive everything else. I prefer to use variables in my formulae as well as real numbers because abstraction tantalizes the imagination and concepts are more readily visualized this way. Too often, educators have little patience or time for students' questions. As a result, students are often hesitant to ask questions. I think that this is terrifying.
Questions are one of the key indicators of how well students are following the professor's lecture.
To me no question can ever be too trivial and I make every effort to reward and answer inquisitiveness - the key to all science. No course in science or engineering can ever be complete without an adequate laboratory. Here, students who have learned the material first in lecture from a theoretical standpoint can see firsthand the practical application of their knowledge in the real world and believe with their eyes what was taught to them in lecture. Sadly, the laboratory programs in many learning institutions in our nation are often the most neglected due to inadequately trained faculty, prohibitive cost, breakdown of equipment not readily replaced or repaired due to insufficient technical support, and lack of interest amongst students. Knowledge is like a living organism that needs education to preserve it.