Monday, January 13, 2020

Having Fun With Computer Science

There is no question that there are a lot of ways to have fun with computer science. Some of them are inexpensive. Some of them cost a lot of money. You can do a lot for a little bit of money. But some interesting things cost more money for computer hardware (especially graphics cards and CPUs), for special software (not everyone offers free versions for schools) or special hardware (A Micro:Bit is pretty inexpensive but an Oculus Quest is serious money).

So what is a teacher to do? Well, there are grants out these. Often very competitive though. There is Donors Choose which is not an option if you are at a private school with a budget that makes public schools look rich. There is teacher spending their own money. Or there is just offering what your school can afford even is that is old hardware and free software.

Now you can do a lot on the cheap. No question. But what I wonder about, as with many things CS education related, is access. Who gets access to the state of the art, bleeding edge stuff and who gets to see “where we were 10 years ago?”

Who gets to program virtual reality stuff and who gets to program the next Pong? When we look at costs for computer science we tend to think mostly about teacher costs or finding room in the building or the schedule. Computers come next but someone who spends their who life on their phone or a web browser may not appreciate why students need a computer with a lot of memory, a fast CPU, and a late model graphics card. Maybe when today’s students become school administrators or school board members that will change but right now getting more money for hardware can be a tough sell.

We’re used to vocational students needing state of the art resources. Computers for reading diagnostics for the automotive students. The latest silkscreen equipment for the graphic artists. The latest medical learning tools (have you see the CPR training dummies lately?) for the medical prep students. But somehow we don’t always see the need for the latest for computer science students. Especially in comprehensive high schools. Some serious CS students might be better off in a career/technical high school for CS. Seriously, some of them are really good at getting the latest stuff for learning CS.

Which brings me back to access. CS is more than vocational. A lot more. How do we show students the real potential if they only have access to what is cheap?

Note: This post inspired in part by Garth Flint’s blog post (Computer Science on the Cheap does not always work), a comment on that post, and things David Renton is doing with his students and Virtual Reality.

Friday, January 10, 2020

How Do Teachers Without CS Experience Debug Student Code

My Programming Honors students are wrapping up their semester projects today. Actually they should all have been handed in by now but I’ll give them until the end of the day. In any case, my students have come up with some interesting and difficult to solve bugs. One involved a png file that had an unexpected transparent  section. The other was more confusing and I’m not sure I could have solved it without a good bit of CS knowledge. Even then it was not obvious. (Long story short – passing addresses can be tricky )

I wonder how less experienced teachers handle the really hard debugging tasks. I’ve been writing code since 1972 and teaching beginners for about 15 years. I have seem a lot of errors. A LOT! Often I can debug code without even looking at it. Some errors are that common. And of course I have developed a lot of ideas about debugging. The debugger in Visual Studio is very familiar to me as is how to use it to narrow things down. Students are very good at finding new ways to mess things up though.

I saw a Facebook post from a teacher who has been assigned to teach AP CS A but who has no coding or CS experience. No, really, I’m not making this up. How in the world will they be able to help debug code? And forget about teaching/modeling debugging practices.

Over the years I have had a number of teachers ask me to help with debugging student code. I saw a very interesting recursion problem once. Doing a stack trace was key to that one.

Debugging may be the single biggest reason to say that one week crash courses are not enough for professional development of new CS teachers. A full semester course would be a good start but without experience a new teacher is going to be just barely staying ahead of their students.

But how to you teach debugging? Have you ever had a course or even just a class on debugging? I haven’t.  How would such a course run? Anyone know of a syllabus for a course like that?  I’ll have to think about that one. In the long run though they is no substitute for experience.

Tuesday, January 07, 2020

What does “doesn’t work” mean?

Every computer science teacher has heard it “My program doesn’t work. What is wrong with it?” Sometimes they will show you the code without any more explanation than “it doesn’t work.”  One generally replies with something like “define ‘doesn’t work.’” Or you are told the program is giving an error. When you ask “what error?” you get a blank stare. The student has shut the error message away without reading it. Somehow you, the teacher, are supposed to know the answer without really knowing the question.

Debugging seems to be the hardest thing to teach students. To be fair, debugging is hard. One quote on my bulletin board is:

“Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.”

- Brian Kernighan

There are a few good, and easy, places to start though. One of them is actually reading the error message. For some reason that doesn’t seem to occur to many students. Of course they often don’t read the directions either so I probably shouldn’t be surprised.

Giving some serious thought to the error message is often enough. To be fair, I like to be fair, some error messages are less than helpful. Helping students to understand the error message is better in the long term than just telling the student what they did wrong. Why do you think the computer doesn’t think that variable exists? Did you spell it right? Did you declare it in the wrong place? Remember when we talked about scope?

Another helpful technique is to explain what the program is supposed to do, how it is going wrong, and how you think the code is executing. Many teachers use the rubber duck scheme and ask students to explain all of this to the duck. This works for some people and some errors. I don’t have a classroom set of ducks but do have students explain that to peers. Sometimes that is enough. Sometimes it is not.

When they explain things to me I often prompt with questions. Often students are wrong in their explanations. I remember one student telling me that of course the code did something because here it was in the comments. There was no code to execute what the comment described but the student thought the compiler actually read the comments. Sigh.

In all cases it starts with knowing what should be happening and what is or is not happening. The more detailed one can explain that the easier debugging becomes.

Thursday, January 02, 2020

A Brief Career Memoir

Blame Mike Zamansky for this one. In my last post I mentioned that I am planning on retiring from the classroom this spring. Mike wondered how my perspectives have changed over the years and through different aspects of my career. Now my career (so far) has four main parts. I worked in the computer industry, mostly developing software, for about 18 years. After a big layoff I went into teaching for about 9 years. Microsoft hired me away to work with educators. My job was to promote Microsoft products for teaching computer science. I spent 9 years there. Seven of them awesome. Management and priorities changed and I found myself leaving Microsoft and after a brief hiatus returning to the classroom seven years ago. It’s been a ride for sure.

During my first 18 years I didn’t see computer science as something for everyone. Education was important and I was involved. I was on the board of a private Catholic K-8 school for 6 years. I was twice elected to 3 year terms on the local public school system’s budget committee. I mostly saw computers and something students needed to be literate in. That meant applications. I believed, and still do, that computer applications can be powerful learning and teaching tools. I saw computer science mostly as vocational. It was, after all, my vocation.

After a layoff, the school I had been on the school board for hired me “while I thought about what I wanted to do” as a part time computer teacher. For the most part, in K-8, that meant typing and computer literacy. I picked up another part time role at a K-6 school and worked at those two schools for a year. My son was in a private Catholic high school and one night at parent teacher conferences I had a long talk with their computer science teacher. I started teaching there the next school year. I stayed for eight really goods year.

I was hired to teach HS CS in 1995 and it was rare for a high school to have one computer science teacher let alone two. But the administration believed that computers and computing was important. It was important to parents as well and we developed a good program. We still taught a lot of computer literacy and applications use but we were having some fun teaching real computer science as well. I still saw it mostly as an elective though.

We moved from a mini-computer (PDP-11 running RSTS/e) to PCs during my first few years there. I posted about many of the changes were were making to curriculum and tools to social media (mostly email lists of course) and caught the eye of someone at Microsoft. We were using Visual Basic for programming and Office for applications. This lead to some side gigs with Microsoft as I helped other teachers learn about teaching CS with Microsoft tools. I got a lot of training and previews of software during that time. Microsoft was developing the .NET Platform and the C# language both of which I adopted for my own use. In my eyes, C# fixed the things I didn’t like about Java.

Microsoft was forming a new group of what they called Academic Developer Evangelists whos job was to promote Microsoft platforms and tools to university professors.  Eventually they hired me on. Note that I joined Microsoft because I believed that Microsoft tools were good teaching tools.  My combination of technical knowledge and education experience was a natural fit for one of these rolls. Over time I expanded my portfolio from New England Universities (I joked that my territory was from Dartmouth to Yale) into high schools.

Computer science was growing in high schools and I really wanted to help make that happen. In my role at Microsoft I was able to give away a lot of software and help create free curriculum resources. I also met with teachers all over the country. The big lesson that I tried to bring back to corporate was that teachers wanted to teach concepts not tools. Curriculum had to be content and concept based not product based.  Sure you need to know the tools and I did a lot of workshops on using them. Using the tools to teach concepts was more important to me, and still is, than the tools themselves. I like to think that the resources we created and gave away were help in teaching more than the tools themselves.

During this time people were starting to talk about computer science as being more than vocational. Not so much at companies but by educators. Microsoft saw computer science as the environment that they lived and did business in. They saw promoting computer science education as not to provide them with more workers, they could get all they wanted, but to help their customers and prospective customers get trained people for their businesses. Still pretty vocational of course.

Others, ACM and the fledgling CSTA were starting to promote CS education as being more about understanding the world around them. I really wanted to be involved in CSTA and I was. I was lucky enough to serve on the conference committee for a couple of years. I have no doubt that my being at Microsoft was at least responsible for that but I didn’t care. I was involved. The conference was and is important.

When I left Microsoft I ran for and was elected to the CSTA Board. That was awesome!

Microsoft moved on in priorities but happily  they gave a lot of support to Kevin Wang and the TEALS program he created. My perception is that Microsoft’s support for K12 CS has moved from product based to supporting CS education more broadly. MS Philanthropies made a huge contribution to CSTA not long ago. I still wish they had someone in my old role but that’s life.

But I digress. 

Leaving Microsoft  and returning to the classroom was interesting. Over the previous years I had met, talked to, learned from, and made friends with CS educators all over the US. I was anxious to bring what I had learned from them into my own classroom.  I was also starting to see the need to computer science to move from the vocational to the core of a good liberal arts education. My years at Microsoft had let me see how teachers were doing more cross curricula learning. Bootstrap, perhaps being the best example – learning math and programming/computer science as mutually supportive. Emmanuel Schanzer is one of my heroes for his work at Bootstrap. So how do we make computer science relevant for everyone? And how do we get schools to make the learning happen?

Over the last decade I have been privileged to work on a couple of curriculum initiatives. The ACM/IEEE CS 2013 Task force which gave me great insights into higher education curriculum and the broad field that Computer Science has become. The  K12 Computer Science Framework which really opened my eyes to the possibilities of computer science before high school. I was also a part of committees who put together CS Teacher certification and K-12 standards for the state of New Hampshire.

It’s been a journey but I see computer science as a lot more than a vocational track in schools. With things like artificial intelligence, Machine Learning , virtual and augmented realty, big data, cloud computing, and the Internet of Things growing in importance in our daily lives I see understanding CS as being as important as understanding some basic physics, chemistry, biology, and yes, even math.

Wednesday, January 01, 2020

A 2020 Vision

Sorry. You may be as tired of the 2020 jokes and puns about the new year as I am. I’ll try to avoid them in the future. This is the time of year I look at the last year and think about what I should try to do in the new year. This year is a bit different. I am planning on retiring from the classroom in the spring. I’m not sure exactly how I will be filling my time after that. Part of me wants to find some other type of job. At the least I want to stay current with computer science education and help teachers and student where, when, and how I can. So this blog will continue.

I’m also presenting at this summer’s CSTA Annual Conference. I’m looking forward to that. The conference itself as well as my presentation. Looking at the program, I think I will be looking at different sessions than in the past though. Usually I would focus on sessions that have the most applicability to the courses I would be teaching in the next school year. This time it will be all about my personal interests without concern about specific courses. I have to keep learning.

Monday I go back to school. One more semester of teaching. I’m going to do my best to make it the best year yet. After that? Well, a lot of possibilities. Should be fun.  

Monday, December 30, 2019

Looking Back on Blogging

Both Doug Peterson ( and Mike Zamansky ( posted to their blogs about blogs from ten years ago. It was pretty interesting. Mike did some analysis of his blogging rates over the months and years. I took a look at my blog posts from ten years ago. I was posting on two sites back then. One a Microsoft owned platform which was my main blogging site at the time. I was cross posting some things to this site as well. Ten years ago this time of year I was posting about projects involving random variables, talking about Monte Carlo simulations, and roulette and slot machines.

Rather than look at ten years ago or do some sort of data analysis of the last ten years (complicated by two blogging sites) I thought I would look at this time as far back as I could. So 14 years ago at the MSDN site I posted a rather aspirational look at The Future of K-12 Blogging I wasn’t even close in terms of prediction.

I think more teachers and administrators are blogging. We’re not seeing anything like the expansion of computer science teacher blogs I was hoping for. I like to think I made a good case for it and that it is still a good case.

Every computer science teacher should have a regularly updated blog. Actually I would like to see every teacher have a blog but for the short term I will settle for computer science teachers blogging. There are several reasons for this.

  1. We need to build a community of practice in CS education. We need computer science teachers, who are generally alone in their building, communicating with their peers, sharing ideas, and supporting each other.
  2. The technology aware teachers need to set an example for the rest of the teachers. If they don’t use technology why should a social studies teacher?
  3. Most importantly, blogging is a wonderful way to share information with your students and their parents. Post links to extra resources along with a recap of a recent lecture. Give students an opportunity to comment on a current assignment or a recent test question. Expand the discussion and the learning outside the bell delimitated world of the classroom. Teach!

I'm really grateful to the CS educators who are blogging though. Mike Zamansky, Garth Flint, Doug Bergman, and Mark Guzdial have been particularly helpful to me learning and thinking. There are others listed at my Computer Science Education blog roll.

Friday, December 27, 2019

Looking Back on Computer Science Education 2019

Christmas break for me until 6 January 2020 and with Christmas over I have some time to think. 2019 was an intere3sting year in CS education. States continue to adopt more CS in K12. Teachers are still in short supply but so to are schools looking to hire them. Schools or perhaps school administrations and school boards, are slow to roll out more CS education. It looks like more schools are offering it which is great. But they are net requiring it so while they meet to checklist of offering CS it is still not for everyone. It’s going to take a while.

AP CS Principles continues to grow in enrollment. I try to get excited about that but it’s hard. AP courses attract too small a subset of the over all population. While there is much to like about AP CS Principles I can’t help but believe we need some more interesting CS courses. Something with depth and an interesting and motivating outcome. The Create task is not that.

Every year I think that the Internet of Things will take off in CS education. The mix of bytes and atoms seems like a natural to me. That didn’t happen in 2019. Perhaps because there is no one promoting it.  I plan on retiring from the classroom in the spring. Maybe after that I will have to time to really dig into it. Who knows, maybe I’ll come up with some good project ideas.

Cloud computing grew a bit in interest in 2019. Amazon Web Services has done some great work on this. Uptake has been slow but at some point it may take off. The problem with cloud computing, and perhaps IoT, is fitting it into the curriculum. It doesn’t fit easily in either AP CS course and too many teachers are working and teaching too many preps to adopt major new topics.

Artificial Intelligence took a jump in interest that surprised me a bit. There was a huge birds of a feature on the topic at last summer’s CSTA conference. AI for K12 has its own website, mailing list, and lots of people interested. See for more on that.

What sort of Artificial Intelligence can you teach in K-12? Mostly how it is used, how to use existing AI tool and machine learning training systems. Developing real AI takes a lot of math that not many K-12 students have yet. Still, it is very important that students learn this much. The need to know what AI/ML is, how it is used, and discuss the ethnical considerations involved.

As always,the new year is full of potential. K12 CS is on a growing path that seems to have some momentum behind it.  I can’t wait to see what it brings.