Designing CS101: From Causes to Learning Obstacles

Let's recap the process of designing a learning experience for introducing computer science to non-CS students. What mistake is the target audience making that they care about? I chose "many people are missing out on a satisfying career." Why do they make this mistake? There are many causes, especially sociological ones, but I chose "people don't get to see what computer scientists actually do." They may take a programming course, often with "exciting" assignments like printing an amortization table. They may someone in a movie or TV show rapidly typing cryptic text on a computer screen. They may get to take a course programming games or robots. Unfortunately, none of these are accurate depictions of what we spend our days doing in CS, namely coming up with new ideas for old problems, or even better, new problems. For me, the neat part of CS is that I get to come up with ideas that may change the world. I can do it with surprisingly small resources, compared to other transformational disciplines like medical research.

Sp now the question is to identify why a learning experience is needed. You don't need course for walking, ordering food in a restaurant, going to school, playing videogames, etc. You learn these and many other things by watching other people do it, and/or trying to do it yourself and learning from failure. We only need courses when this natural process doesn't work. That might be because there's no one to watch, e.g., a master violinist practicing techniques, or learning from failure is not an option, e.g., brain surgery, or a handful of other reasons.

So why don't people learn what computer scientists really do naturally? I think it's pretty clear that it's because there's no opportunity. Most people don't mix with computer scientists doing their job. TV doesn't show it because there's nothing to watch. An intro programming course doesn't help, because programming, while critically important, is not the career. If you don't get people to understand being a doctor or medical researcher by making them take an anatomy course!

So I'm going to answer the third question with this: "people don't get to see what CS is really like simply because there's no opportunity to be exposed to people doing CS."

Designing CS101: From Failure to Causes

So far, I've argued that the goal for a CS principles course that makes the most sense is to deal with the failure "students who don't know what CS is about miss out on a chance to find a career they'll really enjoy in software development or computer science."

The next question then is "Why do they make this mistake?" There's a lot of data on this, particularly for females and minorities, e.g., to pick one pretty much at random, this survey-based study. In this study as in many others, the usual reasons given for not pursuing computer science is that it's too hard and computers are boring. Other studies and articles have focused on beliefs that computer science is all about programming and that that is a solitary activity. Yet others have focused on the presence of role models, again particularly for females and minorities, and the image (or lack thereof) of computer science in the popular media.

I have my doubts about that last one. Female hackers have been a staple on 24, NCIS, Warehouse 13, and elsewhere for some time. These reinforce the nerdy image but are otherwise very positive and emphasize membership in a working group over being a loner.

What about the perception that CS is about programming and programming is boring. Are those beliefs wrong?

One approach has been to make programming more fun. Alice. Scratch. Computing and Multimedia. I love these but so far I've not seen them move past the introductory level and hit the place where most agree real CS begins: algorithms and data structures. This also doesn't address the issue of what you do in CS.

Another approach is to skip the programming and go straight to the big ideas. That's what started this series of blog entries. But if the goal is to show that CS is an interesting career, then it' s not the ideas students need to see. That's like thinking a biology course introduces you to what biologists do. Students need to see and try doing things that accurately reflect what computer scientists actually do. What fills their days? What makes them want to come to work? What's a moment of joy?

So, my conclusion is that students misunderstand what people do in CS, besides programming, because they've never seen it done nor had a chance to try doing it, particularly pre-college. In this, CS isn't really different than math or biology or many other fields. Most education is badly constructed around facts and ideas rather than skills and activities. If there was a glut of computer scientists, this wouldn't matter, but as far as most U.S. companies and the government are concerned, we have a growing shortage.

On to question 3!

Designing CS101: Failure-Driven Course Design

In Agile Education and the CS Principles Course, I criticized learning objectives like:

• "The student can analyze the effects of computing within economic, social, and cultural contexts." (Objective 4)
• "The student can use abstractions and models to solve computational problems and analyze systems." (Objective 5)

These appear to have no answer to Question #1 in the 6-question framework: What mistakes are people making that matter, and who cares? What goes wrong when people don't or can't do Objective 4? Outside of essays and exam questions in the CS Principles Course, where does this skill matter? Is there some subgroup for whom this skill is critical? Who and when?

With Objective 5, I can think of some people to whom it might matter: computer scientists and software developers. There are two problems though. First, this is a much narrower group than the CS Principles Course is being developed for. Second, I can only say "might" because I need to see typical examples of developers not using abstractions and models, and what the negative consequences are. What's the evidence that this occurs often enough to be of concern, and is harmful when it does occur?

All of the CS Principles learning objectives have this problem, except those directly about programming, such as

• The student can create a computational artifact through programming.

But the point of CS Principles was that there's more to CS that people should know besides programming.

So can we answer Question #1? Let's step back, as good Agile developers do, and ask "what's the goal of the CS Principles project?" Like many committee and community-built curricula, a number of goals have accrued. A summary of them can be found in the Open Letter to the Computer Science community.

One impetus certainly is the feeling by many in CS that most people, including students, teachers, parents, and so on, think computer science means programming, programming is boring, and therefore students choose not to pursue a career in computer science.

That feels like a real mistake, but Question #1 also asks who cares and why? I can think of 3 major groups:

• employers
• the government
• students

Employers care because they need good developers. But that's back to programming plus other developer skills. Not where the CS Principles initiative arose from.

The government, especially NSF, cares because they want the US to maintain a lead in research in new forms of information technology. That's good. A CS Principles Course about the big ideas, where they came from and where new ones are coming from, would help address a failure they care about.

Students should care. It's in their own best interests to know whether CS is a career they might actually enjoy and do well in.

So we can argue for a course on how to be a software developer or a computer scientist. But the proponents of CS Principles have a broader aim. Peter Denning in a number of essays on the Great Ideas in CS, Jeannette Wing in various essays and talks on Computational Thinking, and others, have said that a big mistake students make is not knowing how to approach problems in science, engineering, and social issues, from a computational perspective.

The relevant parts in the Open Letter are these two bullet points:

• With a concepts-rich curriculum that emphasizes computational thinking and problem solving students taking the course will be better prepared for most careers, given the role that computing plays in most sectors of American life.
• The population at large -- starting with present day high school students -- will become more knowledgeable and cognizant of computing and computational phenomena.

I'm unconvinced. Students certainly need to be tech-savvy. But they are, often more so, when it comes to social media, than most of the faculty in CS departments. But do they really need computational thinking? Where exactly, outside of programming and CS research, does it matter if someone doesn't apply computational thinking?

I can easily see "here's why it matters" arguments for subareas of computational thinking for subgroups of students. Students in biology should know about multi-agent simulations. Students in cognitive psychology should know about cognitive modeling. There are motivating examples of muddled thinking failures in those and other fields due to the inability to think computationally.

But I'm unable to see why poets, playwrights, and plumbers need to know about computational thinking. Without convincing examples of "why does this failure matter?" a course design is doomed. Students will view CS Principles as yet another irrelevant rite of passage, like learning the parts of a neuron, the lifecycle of stars, the dynasties of China, and so on.

So, I'll stick with the answer "students who don't know what CS is about miss out on a chance to find a career they'll really enjoy in software development or computer science." Phew! One question down, five more to go.

Agile Education and the CS Principles Course

One of the things about the Agile movement that attracted me from the beginning was how proponents would go back to the core goals of development, like "getting something working that the client really needs," and from that develop practices that turned standard development idea on their head. That resonated with my own experiences in how to attack problems like natural language understanding and the design of learning environments.

I recently gave an internal "brown bag" talk on how several of these upside-down Agile practices could be fruitfully applied to educational design and academic research.

Then I happened across the AP CS Principles course, and specifically their learning outcomes document (PDF). I have great respect for the goal, the people involved, and the effort invested, but that "requirements" document is wrong in so many ways that I felt a need to try and articulate why.

My own approach to designing courses and other learning experiences is based on the 6-question framework developed by Alex Kass, Ray Bareiss, Danny Edelson and myself in response to the many flawed designs we'd seen (or created) over the previous decade at the Institute for the Learning Sciences at Northwestern.

Question #1 in that framework, "What mistakes are people making that matter, and who cares?" is the most critical. It defines what you need to teach. It's where at least half the designs we saw failed, including the CS Principles learning outcomes. Pull out just the statements about what a student will learn to do. Here are two:

• "The student can analyze the effects of computing within economic, social, and cultural contexts."
• "The student can use abstractions and models to solve computational problems and analyze systems."

Try and find any outcomes that a student would say "I can't do that but I'd love to learn how!"

In case it's not clear why this matters, read the UW CSE120 blog on a pilot run of this course. Look where student engagement occurred. Without engagement, nothing else happens when it comes to learning

It's easy to criticize. That's the point of this blog. But it's not enough to criticize. What would a better answer look like? What would happen if I applied the 6-question framework to the course with the same intent as the CS Principles course?

That's my plan for the next several blog posts. Stay tuned.

Critique-based Assessment

I said that in my programming courses (and others), I'd rather critique than grade, because grades are such a bad idea.

[And I'm not alone. Alfie Kohn's nice post references similar criticisms as far back as 1933!]

But schools want grades, and therefore so do students, so how do I assign grades at the end of a term?

Here's how my critique-based courses work. Instead "do it once, get a grade, repeat," the process is "do, review, re-do until mastered, then move on." More specifically,

• Students select and work on assignments (exercises, projects, ...).
• Students submit their best solutions to each problem.
• I critique each solution, pointing out weaknesses and areas for improvement.
• Unless the critiques are non-trivial, the student needs to re-do and re-submit. This happens for most initial submissions.

Quite quickly students begin separating out. Some zip through the early easy stuff, some need a lot of tries to get the basics down. In a standard course, the latter students would be forced to face more and more complex problems with incomplete skills, while the former students would be bored waiting for the challenging stuff.

At the end of the term (and usually at one or two mid-points), I calculate grades based on

• progress, as measured by the number, range, and complexity of assignments completed to this point,
• mastery, as measured by the lack of serious basic critiques in the solutions initially submitted, and
• effort, as measured by the number of submissions and re-submissions.

During the course I get to focus on what I care about: what problems are students having and what advice should they be given. There's no repeated reduction of wildly different points into singular point values. As a bonus, I get a detailed current picture of what students are having the most trouble with.

When I describe this to other faculty, the usual response is "whoa, that must take forever!" Indeed, without some kind of tool support, it would not be feasible to give detailed feedback like this to a large class, and it would be very time-consuming and error-prone to review and evaluate each student's history of interactions for an entire class.

Fortunately, we have the technology. Next time...

Critiques, not Grades

When teaching programming, I critique code, I don't grade it. Despite their ubiquity, grades have many problems. In no particular order, here are some big ones:

• For any solution complex enough to be worth evaluating, a single number is way too inadequate a measure of quality.
• Calculating a weighted average of inadequate individual grades to get a final grade makes things even worse.
• Who would you rather have working for you: someone who got 5 programs 80% done, or 4 out of 5 programs 100% done?
• A grade provides no useful feedback to the student on what was wrong and how to do better.
• Grading requires repeated arbitrary decisions about the relative demerits of misleading function names, bad indentation, failure to use standard library functions, and so on, when all I really care about is whether is something worth fixing or just noting.
• The students tune their behavior to optimize their grade based on whatever arbitrary rules I developed.

But if I don't grade, only critique, how do I figure out a final grade? Next time...