I'm writing this column as therapy, a break from grading the final exams for my course. Samuel Johnson once described a second marriage as the triumph of hope over experience, and I see a sort of parallel with teaching and then grading. Every semester begins with a burst of new energy and a brand new group of some of the smartest and nicest people one could ever hope to meet. I spend the whole semester getting to know them, while talking about interesting and important topics. This is the "hope" part, and it's nothing short of wonderful.
Then comes the final exam and the "experience" part: every year I discover again that in spite of my best efforts, and certainly the best efforts of the students, not everyone learned everything that I had hoped to teach them. This year, pretty much everyone mastered the difference between a bit and a byte, and most proved able to make the distinction when it mattered; that's an improvement over some previous outings. A discouragingly large number still don't grasp binary numbers, and certainly not how to do simple arithmetic on them. Indeed, it seems that some don't even know how to do arithmetic on decimal numbers, at least under time pressure. I'd feel more superior about this if it weren't for the fact that when I checked my own arithmetic, nothing more complicated than adding up points for various questions, I found errors in two or three of the first five.
One hopes that students will hang on every word of a lecture and remember it clearly for the exam. But experience shows that recall is less than perfect: some students appear not to have to been in class at all, and some of those who did attend were present only in body, devoting their classroom time to sleeping or surfing or socializing. I did get full attention in a few lectures, however, notably the one where we examined MPAA and RIAA "cease and desist" letters sent to OIT about students who were uploading allegedly copyrighted music and movies. The letters are interesting in themselves, and they are based on technical topics from the class, like IP addresses, peer-to-peer networking and digital signatures. In one of those golden teaching moments, a student said "Suppose, just hypothetically, that a student was caught uploading an MP3. How did they know?" Suddenly the whole class was on high alert, and we had a great discussion about this purely "hypothetical" situation. I haven't gone back yet to see if I can correlate attendance with how well people answered the final exam question about this topic, but I'll bet that those who were present did fine.
Why should one have to know any of this technical stuff? I think it matters if one is to be an educated citizen. For instance, surveillance equipment is getting cheaper all the time. How cheap? One of this year's questions asked a peripherally related question: how much disk capacity would you need to store everything you're heard in your whole life? It's not much, about 10 terabytes (work it out — get 5 points on my exam), which even today would only cost a few thousand dollars, and which will likely cost less than a hundred dollars by the time today's freshmen have graduated, thanks to exponentially falling costs. Video is at most 10 times that.
Energy costs for Internet servers are growing at about one percent a month. When will today's gigawatts for servers become terawatts? (Another five points.) Parents can now buy systems that will monitor where their teenagers drive and display the results on a map via the Internet. How might this work? What is the main concern about the impending purchase of DoubleClick by Google? What's the technical issue behind the current European Union vs. Microsoft fracas and how does it relate to the ongoing battle in the United Stag=tes that began nearly 15 years ago?
One of my questions came from the current presidential campaign. When John McCain made the now obligatory stop at Google in May, he was asked one of their standard interview questions: How would he sort a million 32-bit integers in only two megabytes of RAM? Great amusement from the audience, of course, and Eric Schmidt '76 let him off the hook quickly. But wouldn't it be striking if he could have answered the question or perhaps the variant of it that I subsequently asked on my exam? When Barack Obama was asked the same question in the same setting in November, he gave a witty and technically correct answer. (There's obviously some alert geek on Obama's campaign staff.) I'm delighted to report that the majority of my kids got it right too. It's clear that they'll be ready in a few years when they're starting to run the world, and I for one am looking forward to that. Brian Kernighan is a professor in the Department of Computer Science and is a Forbes faculty adviser. He can be reached at email@example.com.