For years I've been one of the few people banging the "CS teachers must know CS" drum. There have been a few others out there but in terms of being vocal about it, we're in the minority. I get it. There are many teachers who volunteered to teach CS and are working hard to acquire the knowledge needed. There are also those who were voluntold who are trying just as hard.

The problem is, at least from what I've seen, there are far too many CS teachers who after years of training still can't navigate CS1 or sometimes even CS0 level code and have very limited context when it comes to CS. They know the bullet points in the scripted curriculum they're using but that's about it.

I also get that it's not easy to be vocal about it. When I talk about this, it can seem like I'm calling out my CS teaching colleagues and while in a way I am, I'm talking about those who've stayed at barely CS0 for multiple years, not those working to improve their CS knowledge.

I was reminded today why this is a problem, why people should be paying more attention to it and why more should be calling it out.

I was chatting with a young man today. He has a Math and CS background - was a double major, and is considering a career change from a non teaching job in to either teaching or something education adjacent.

One thing that came up in our conversation was that he took a CS class in high school and that almost caused him to drop the field. My new friend mentioned that the teacher in question was a math teacher and a pretty good one at that but noted that in addition to not knowing the CS, the teacher didn't know how to teach a CS class. Of course, my friend acknowledged that he's not a teacher himself but the end result to him as a student was that he was turned off.

In college, in spite of that bad experience, he decided to try CS again and after a couple of nondescript courses he took one that he described as life changing. A great instructor that reignited his love for the subject.

This happened to me as well but on the math side. I was always pretty good at math and enjoyed it, until I wasn't - this was Calc II. I thought I just hit my wall and I started to dread math even though I knew I'd need some to be a CS major. I figured it must be me. I slogged through my required courses in college barely getting by until I took Discrete Math - the instructor was "just" a grad student but he was terrific. Turned me back on to math. I realized I could do this stuff. A couple of years later, I realized that my problem wasn't that I was stupid but I had a bad teacher who didn't teach me what I needed to know to succeed in Calc II.

We always here about that small handful of teachers that many of us had who inspired us or set us up for our futures but there are also many tales of that bad experience. That reason why someone is math phobic or why they abandoned some prior passion. Maybe it was a bad teacher, maybe a good teacher severely out of their element but throwing kids into a CS class with an unprepared teacher just to say they got to take CS might not be the best idea. We might be exposing them to the field but we also might not and worse, we might be turning them off. If the teacher is well prepared, all good. If the teacher isn't but recognizes their deficiencies they can still pretty much ensure that they won't be harming students and some good will likely come out of the class. An ill prepared teacher who doesn't know any better can be a dangerous thing.

This of course isn't to say that there's one way to prepare a teacher or for a teacher to be prepared and certainly there are many ways for said teacher to run their class. In my conversation today, my new young friend shared thoughts on a few of his CS teachers noting how many of them did things very differently from each other but they each played to their strengths and to my friend's view, the were effective.

I'd like to think that this situation will ultimately work itself out, at least in states that have strong credentialing but even there, we could have issues as I've seen CS credentialing programs that barely cover CS0. If we want to make sure that ALL students receive strong CS education, it's up to all of us in the community to call out the situations preventing that and that includes calling out bad prep programs, bad PD, and schools and districts that tolerate or even encourage CS teachers who don't know CS.