Archive for March 1, 2011

Improve Computing Education: Take the More-than-Java Pledge

I have a sure-fire way of improving computing education.  Everyone reading this, post this to your blogs and Facebook status and every other way that you make public, digital statement these days:

I promise to no longer teach Java to anyone at the undergraduate Freshman level or earlier.

I am teaching Java in my Media Computation Data Structures class this semester, the first time I’ve taught first year students in four years.  I had forgotten how bad Java is for beginning students!

My students are almost all non-CS majors.  This is all their second semester CS course, but for the most part, last semester was the first time any of them had ever programmed.  Their first course was in Python (robots), Python (MediaComp), or MATLAB.  It’s a small enough class that students actually do come to my office hours, and that lets me see the aggravating errors that they are facing.

Here’s a common error — it’s a faulty method declaration.

public void foo();  
    // blah, blah blah

The error you get is: missing method body, or declare abstract.  Sure, that message makes sense if you understand about semi-colons and blocks, but if you don’t…”What’s abstract?!?  I have a method body there — why doesn’t it see it?”

Here’s the one that I saw multiple times (both versions), which I find just infuriating.

while (a < 4);
    // do something in here, and probably change "a"
if (sometest());
   // do something if true

These are infuriating because there is no error — the first generates an infinite loop, and the third one just always executes the body, ignoring the result of the test.  Programs don’t work, and the compiler gives no clue that the students did something that only experts can handle correctly.

I’ve read Kernighan and Ritchie.  I know that, with magical side-effects and complex C-magic, one doesn’t actually need to have a body on loops and IF’s.  Everything can be done in the IF or WHILE test, or in the body of the overly-complex and macro-like FOR loop.  But why allow that in a language for beginners?  We’d never want to teach that to first year students, and by allowing these experts-only practices in Java, we lay land-mines for them!

I completely believe that students should learn C-based languages, and Java is a powerful tool that most CS students should learn.  But not to start.  It’s a lousy language to wrestle with when you are still trying to understand what commanding a computer is all about.  My students are trying to understand object interactions and creating dynamic data structures, and errant semi-colons are eating into all of their programming time.  Seriously — a bad semi-colon may cost a starting student 30 minutes of programming time (as Matt Jadud’s ICER 2006 paper showed).  If you can only afford two hours of programming time for an assignment, one wrong semi-colon now means you only have 90 minutes.  If you can’t complete the assignment, you never get the motivation boost of success and your grade suffers.  I really believe that semi-colon errors correlate with our retention problems.

So why do we teach Java so early?  Because it has become the language of CS education.  We have to teach Java to prepare students for what comes next.  This is particularly salient for me because, as of this semester, we no longer teach Smalltalk to students at Georgia Tech.  Lisp died from our curriculum about a dozen years ago.  Now, the required courses teach (in order): Python, Java, Java, C, Java, and options in upper-level courses between C, C++, C#, and Java.  If students want, they can take a specialty course where they might see some ML.  I don’t think GT undergraduates can even take a class where they’ll use Lisp anymore.  C has won.  This is a learning problem because I worry that students won’t develop cognitive flexibility without these other language approaches. Forget about transfer, forget about vocational training — let’s focus on being able to think about problems and representations in different ways. Here’s our goal in Rand Spiro’s words (which weren’t about programming, but fit perfectly): “Cognitive flexibility theory suggests that learners grasp the nature of complexity more readily by being presented with multiple representations of the same information in different contexts.”

The real tragedy here is that few of us can take the pledge.  I can’t take the pledge, either.  We live in an educational ecology, and none of us can act alone. If I did, then I would be doing my students a disservice — they would be unprepared for their later courses.  If high school teachers took the pledge, then they couldn’t teach AP CS, and there would be even less high school in CS.  And no, that wouldn’t be a good thing — by every study we have, students without a CS course emerge from high school with extremely ill-informed and negative views of CS, and any high school CS makes things better.  High school students with CS have a better understanding of what CS is, and are more likely to pursue later studies.

How do we get to a better place from where we are now?  We who teach CS all have to decide that there’s more to programming computers than C, that 1973 was not when humans reached their peak in ability to communicate with a computer.  We have to recognize that other forms of programming are important, even if it doesn’t get students a job.  And by teaching those other languages, perhaps we create a seed to change industry, too.  We just can’t settle for what we have now.   We have to decide to teach other kinds of programming languages (somewhere!), and to create pathways so that we don’t doom students who don’t have Java in their first year.

Here’s a pledge that I hope that all computing faculty can make:

I pledge that I will work with my colleagues so that all of our computing undergraduates will learn a programming language that is not based on C, and we will build that into a required course within the next two years.

March 1, 2011 at 8:20 am 63 comments

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