It's obvious, right?

My first calculus professor used to tell a story about a professor who was lecturing one day in another class.

He had equations drawn across 3 different black boards and came to the end and said, “and the result at this point is obvious…”, but his voice started to trail off at the end as if all of a sudden he was not absolutely sure. He stood at the board for a moment, then reviewed the other two boards, then looked at the ceiling and waved his hands a bit, and then found and empty spot on the board and wrote a few more equations, then looked very puzzled and turned to the class and said, “Just a minute, I will be right back” and left the room.

The professor returned several minutes later, walked back to the board and said, “yes, it is obvious” and continued with his lecture.

My professor’s point was that we have to be careful that when we say it is obvious, that it really is actually and honestly obvious. Obvious is not just a word to be used to make it seem that we are right with no explanation needed and no argument possible. Statements like, “This feature needs to be changed for obvious reasons.”

That is a great thing about this community - for obvious reasons. :wink: No, actually because we discuss all of these issues openly because the same right answer is never obvious to all of us at the same time.


And, that reminds me of another story: I was in a computer science class and the professor was reviewing for the final exam by going over past exams with us. He was going over the QuickSort algorithm. He worked through the solution and got near the end and said, “and here is the trivial case and we don’t need to take time to go over that because it is obvious.”

I raised my hand and said, “Professor, would you please go over the trivial case for us and explain how it works?”

Prof: No, we don’t need to do that.
Me: I would really appreciate it if you would at least for my sake.
Prof: No, it is a waste of class time. If you really don’t understand it, see the assistant.
Me, Professor, your solution does not work.
Prof: I have used this problem and solution for many years with every section of this course!
Me: It is wrong.
Prof: Fine, let’s waste the class’s time for Bob.
Prof: Here, look, it works like this…
Prof: Damn!!! What the…!!! Oh, @ #$!% !!!
Me: Hmm, do you want help regrading all of those past years of Final Exams?

When grades came out, I got a D. I went to his office and asked about it and he said, “Oh, my grader must have recorded it wrong. I can change it to a B.”

Me: Is that the best grade I can expect from this class?
Prof: Yeah, I think that is the best I you could possibly expect.
Me: Well, thank you.

Of course, neither of us ever had a class together again…until,

One day I was lecturing as a substitute for another professor and this guy walks in because he is auditing the class. We smile at each other and he says, "You are lecturing today? " “Yes sir” and he turns to leave. “Shall I mark you ‘not present’ for the lecture today sir?”


I had something similar in a computer science lecture.
The prof showed us an simple compression algorithm, including to compress and decompress some letters on the board (no programming involved at all).
So I decided to code the algorithm at home.
It did not take me long to find out that the algorithm does not work in all cases.
A simple sequence of 3 identical letters at the beginning could never ever be decompressed back to this 3 letters.

So at the next lecture I confronted the professor with this fact.
She (yes it was a she, not that this has anything to do with that) says that’s not possible.
Me: I can show you a simple example that it does not work.
Her: I don’t want to
Me: I can proof it does not work
Her: well this might be true, but you know, ehm, …, This class is not about teaching you actual algorithms, but only to demonstrate how it could work
Me: :wall:

And people wonder why I only ever attended 3 classes per course. I’d attend the first class to get the course outline, attend to write the mid term and then the last class to find out about the final. Of course I did all the assignments etc but I found it a lot less frustrating to just do the learning on my own (really used to piss some profs off when I wouldn’t attend their lectures but yet ace their course, like they were the sole source of knowledge on the course topic). But still you have tip your hat to them for enduring the system sometimes.

That was my strategy as well (more or less).
Some classes you had to attend. But in some the prof just read the script, which we had anyway.
One of them removed words and sentences from the script you had to fill in.
Fortunately the script never changed over the last ten years ::slight_smile:
But finally I didn’t care much about my final grades: 4 wins :whistle:
Even by this the average grade did not turn out to be too bad at all, and I had enough time for my programming side job to have a sports car and a motor bike :dance: