I wanted to give a little more context on yesterday's post. In reading over the various comments on social media related to the topic of required and desired CS teacher knowledge there are those that fall on the content is king and pedagogy not so important and others who think you don't really need a deep knowledge of CS. I think you need both and think current teachers need to be given a reasonable but finite amount of time to get there.

There were a few posts over on Facebook this weekend about teacher certification. It started with a question - should teacher certification be based on an exam like APCS-A with the teacher correctly answering 85% or greater. A lively discussion followed. There was agreement and disagreement with responses ranging from: good idea it's too hard it's not hard enough There was also a discussion of the importance of content knowledge vs knowing how to teach in general.

Lots of chatter with Donald Trump being kicked off platforms left and right. On the one hand we're getting a lot of "it's censorship, it's unust" and on the other side we have "it's about time." I'm of course in the "it's about time" category but even so, there's a cause for concern and a lot of meat for a discussion on tech policies. What makes this interesting discussion fodder is that Trump was removed from different levels of the internet.

Yesterday I read three posts on teaching recursion. First by Shriram Krishnamurthi discussing his thoughts on how recursion is taught incorrectly. This prompted Adam Michlin to write about teaching recursion later with some commentary on APCS and then finally, Alfred Thompson added his thoughts. Much like everything else in education there is no single right way to do things. To say as an absolute that you should or shouldn't teach in a certain way is wrong - too many variable.

Time for some final thoughts on Advent of Code 2020. This was my sixth Advent of Code but the first time I completed all 25 days. Better than last year's 31 and a whole lot better than my weakest effort of 11 stars in 2017. I managed to find the time to finish all but two on the day they were released and finished those two on Christmas morning. This was also the first year I wrote all my solutions in Clojure and I also made a bunch of blog posts and videos (linked on the bottom of this post).

Day 24 didn't take that much time so I had a chance to go back and finish day 21. As usual, all my code is up here. Day 21 Problem Link It took me a while to get my head around this example. You have a set of recipes. Each recipe has a list of ingredients and a list of allergens. Your job for part 1 was basically to determine which ingredients don't contain any allergens.

A few days have past so it's time for an update. Two more days to go and while I haven't completed all the problems, I have accumulated 43 stars which is a personal best. Given the nature of the problems I'm missing, I might even go back and do them at some point. Of course, I may very well also just crash out on the final two days. As usual, all my code is up here.

Day 17 Day 17 brought back Cellular Automata. It was a nice follow up to day 11. In my writeup I talked about data representation - how a Cellular Automoton like Conway's game of life is a nice 2D array project in a class like APCS-A but multi dimensional arrays are only one way to represent a cellular automaton. Day 17 really drove that home. The actual rules were pretty simple - if a cell is active and has 2 or 3 active neighbors it stays active.

Today's problem was a fun one to solve. Why was it fun? Stay tuned, The basic gist is that you have a plane ticket which is a set of numbers but you don't know which number maps to which category - row, seat, gate, etc. You also know the number ranges for each category. For example, row might be a number between 6 and 11 or 33 through 44 while a seat might be 13 through 40 or 45 through 50.

Time for Day 14!!! I didn't write up day 12 but here's a Clojure video runthrough. I also didn't write up day 13 mostly because I hacked together my part 2 in Python and still want to rewrite it in decent clojure. In any event, all my solutions are up on GitHub. Day 14 had a few interesting things going on. At its core it's a small machine simulator where you have to deal with binary numbers.