Usually when I post on this blog, it's to express an opinion of my own. This post is different because I'm soliciting other people's opinions. For probably a century or so, the way high school and college physics classes have been taught included the idea that the teacher would assign homework problems from the book, and the students would solve them. I'm the author of some open-source physics textbooks, and now that I'm retired I'm thinking about whether to make my solutions to the problems freely available on the web. I would love to hear from any physics teachers or learners who have comments on how this plays out today.
Around 1982, when I took freshman physics at UC Berkeley, the teacher would assign a list of numbered problems from our textbook. We would solve them and turn in our solutions on paper. Then a TA would read our solutions, write comments in red pen, and give us a score. While this was happening, the TA would also post solutions on a bulletin board inside a locked glass case in a hallway near the classroom. (God, I'm old.) This was a class for physics majors, so some of the problems were pretty hard, and yes, sometimes there would be a crowd of us out there in the hall reading the solutions through the glass.
These were more or less the practices that I followed as a community college teacher from 1996 to 2021. There was no glass case, but I would pass out photocopies of the solutions after the students had turned in their papers.
One thing I did change was to start using software to let students check their answers. I first saw this demonstrated at Michigan State when I had a job interview there. Students didn't have their own internet access, so they used terminals in the halls of the dorms to check their answers. The software was free and open source. When I started teaching in California, I cooked up my own open-source software for this purpose. Its purpose was to help students know in advance whether they were turning in correct answers, and to drive them in to my office hours if they realized they were wrong. I kept grading homework by hand, and I kept assigning problems or parts of problems that required answers in words. The system seemed to work pretty well.
Then one day around 2005, a book rep from Pearson showed up at my office. Her sales pitch started like this: "Hi, Professor Crowell. You aren't still grading homework by hand, are you?" Pearson had looked at the open-source answer-checking software that was out there, and they had developed their own proprietary system. Their cash cow was (and still is) MasteringPhysics, and they also had similar products for calculus and statistics. Two things were happening here that I think were pretty negative. The first was that teachers were being encouraged to end the practice of actually looking at their students' work, and to stop assigning questions that required answers in words. The second was that this was the killer strategy for getting rid of the used book market. Students were forced to buy the new, overpriced textbook, because it came shrink-wrapped along with a card that had the password for MasteringPhysics (adding an extra $100 to the price).
I kept on doing what I'd been doing, but the next big change came around 2015, when a web site called Chegg came online. Chegg does the same thing that a lot of unethical Silicon Valley firms are doing these days: they scrape the web to steal people's work, and they make money by exploiting workers in poor countries. Today, if you take the text of one of my homework problems and put it in a search engine, chances are pretty good that the top hit will be not my book but a page on Chegg's web site. There you see a teaser for a solution, written by a university student in India. If you sig up for a $20/month recurring credit card charge, then you're allowed to see the solution. Here's an example: google search, top hit. The Chegg system made the students happy, and physics professors also wouldn't notice that anything was going wrong, because remember, most of them were no longer looking at students' written work. The student simply copies the mathematical result out of Chegg and types it into MasteringPhysics.
I'm retired now, and I don't think my open-source books are any longer being used by very many instructors. I'm thinking that the thing to do at this point is to make my own solutions openly available on the web for free. I can't easily ask the teachers who are using my books what they think, because the books are free, so I typically don't know who's using them. Making the solutions openly available would presumably be helpful for people who are self-studying and for home-schoolers. The usual argument I've seen against making solutions available is that many students aren't mature enough to use them intelligently, and many will just turn in copies or paraphrases of them. But to me that seems like an obsolete idea, since Chegg exists.
Ben Crowell, 2023 Jan. 25