# Interesting Problems

I organize a monthly professional development session for CS teachers. It's targeted at teachers who are beyond the beginner stage and don't want yet another hello world blinky arduino scratch workshop. Don't get me wrong, given the need for CS teachers we need plenty of beginner workshops but we also need to take teachers to the next level. I refer to my workshops as being for teachers of APCS-A, similar, or beyond. Participants get three hours of CTLE credit and thanks to our gracious hosts at Digital Ocean get to use a great space and enjoy a free meal.

I particularly enjoyed last weeks workshop for two reasons. One is that we talked about "interesting problems." This in itself is interesting because different teachers find different things interesting. For me, this time around, I was thinking of problems that could be approached by beginners but had some interesting insight that allowed them to look at the problem differently and solve it more efficiently.

The second reason I liked this session is because I wasn't the only one presenting!!!

I started the session talking about the Happy Ladybugs problem - a Hackerrank problem I wrote about here.

I then passed off to Justin who talked about finding the convex hull bounding a set of points. Justin talked about how you can relate this abstract geometry problem to real world problems like bounding neighborhoods as well as how this can be graphically motivated and then moved to discussing algorithms. Students can pretty easily come up with a in inefficient O(n^4) solution and then Justin talked about incrementally guiding them through alternate solutions ending with something that runs in O(nlgn). At the end of the day we had a problem that could be done in a variety of ways with students at different levels of experience.

We then moved to Barry's presentation of a puzzle hunt problem he adapted. It involved decoding, translation, number bases and Barry uses it as a platform to work with stacks.

I finished the evening talking about three problems but we didn't look at solutions. These were teasers for next time when we also hope to do a SIGCSE recap.