This summer I have been teaching graduate students (students going after PhDs in astronomy) about telescope observing and analyzing the data they collect. This week is the last week of summer classes, and so the course is coming to an end. The students are giving presentations on their projects, so my preparation time this week is small. Of course, this weekend I will pay for the week of no classwork when I have to grade six term papers in three days.
I am still amazed at how much time it can take to properly prepare for a class. I borrowed most of my materials from other people, so I had far less to prepare than if I created the class from scratch. Even so, it still took several hours to prepare for each 1 1/2 hour class period.
Sometimes I see claims by people (usually congresspeople or state legislators) that college professors get paid too much and do too little, only teaching one or two classes each semester. Although I knew that these claims were wrong, I now have first-hand experience to see how wrong they are. To prepare and teach a college level class properly takes many hours outside of class for each hour spent in class. So those claimed "leisure" hours are not spent sipping drinks on the beach at taxpayer expense, but spent in pouring over new materials, developing better visual aids, and gently reminding one's self what we are going to say when standing up in front of dozens of students, many of whom would rather not be there.
Are there lazy professors? Yes; as in any profession, there will always be those who fail to pull their weight. But, as in the business world, even tenured professors have to submit to performance reviews and evaluations. Eventually, those not putting in sufficient effort will be weeded out. But this group of people is a minority.
So, the next time you here someone saying that those professors in their ivory towers should try working for a change, know that, in fact, they are working; often 60 hour work weeks, trying to educate students to the best of their abilities while still accomplishing some research work. It's quite challenging to juggle these things, and I'm happy that I have come to appreciate it more now than ever.