Looking over the robots they support, low cost means about "thousands of dollars" in this context, right?
933 karma · joined August 12, 2013
The `World` (which is based on the concept from Racket's Universe library) does indeed get broken down into smaller objects. We talk about how to do that too. The idea is to lead this naturally into more OO stuff next semester, but we talk for a while about how we can use dictionaries to structure data at least.
Obviously, global data is powerful and allows us to do a lot. I let my students define top-level functions and use them globally throughout their programs, and as you say the import mechanism also gives us useful constants and functions to be used anywhere. We talk about how great global constants are for this reason.
The problem is mutation. When you have global mutable state, it becomes difficult to reason about the program. Code written in one part of the program can cause issues hundreds of lines later even though they are seemingly unrelated. You can no longer easily write simple unit tests to confirm that your program works as intended. Global mutable state also frustrates my attempts to use program analysis to give enhanced autograded feedback.
As a concrete example early in the course, we use the Turtle library to define a bunch of functions to write letters, and then they use those functions to write out their names. Difficulty ensues when I ask them to swap definitions and reuse the functions. One kind of issue they encounter is the Turtle library's reliance on global state, which makes it difficult to reason about where the cursor should be after you call a function.
You are thinking about the World example, but what about when they make a list of Coin objects? With global state, they start encountering very mysterious bugs related to the shared coin instances. When its all contained within the World object being passed around, we can write more coherent unit tests to debug this kind of trouble. In a class of 150, it's helpful to give them mechanisms like that.
It sounds like you are hypothesizing that my students have a motivation problem and proposing that I use an intervention of "Selling students on the magic of computers". Based on survey data collected during my past few semesters, I do not believe that my students are disinterested in the subject. This is true at the beginning and end of my course - I cannot claim that my assignments and course design (some of which is particularly oriented towards making the students interested in CS) has a big impact here, but I do not think they are being hurt by that aspect of the course design. There are potentially motivational issues related to self-efficacy, community interaction/isolation, and help-seeking behavior. However, I don't think your proposed intervention would solve those problems.
Instead, I disagree that my CS1 here at the University of Delaware is not the place to discuss the topic of avoiding global mutable state. My curriculum has several learning objectives explicitly oriented around these topics (largely agreed by my colleagues) and I have several projects that I think can authentically justify their importance (particularly with regards to testing and getting enhanced compiler support). I have many anecdotal supports from friends in industry and my own experiences teaching upper division courses that students struggle with issues that can be solved by avoiding global mutable state where possible. Personally, Therefore, since CS1 is not an agreed upon well-defined subject, I think I am perfectly justified including it in my learning objectives, alongside many other important topics and objectives.
If you have demonstrable evidence relevant to my teaching context that teaching global state early could impact areas where my students have other known issues (either motivational or cognitive), then I'd be very happy to read up on those. However, for now, I am doubtful that teaching global state is a serious issue.
At this point, we're leaning towards making our own library to satisfy our purposes. We're still looking at other options though - hey, if you have one, feel free to suggest it :)
A new Pascal would be nice. I loved how much we had to set things up. You start off the entire program by listing out all the variables and types you need! What a fun concept. That would be nice to enforce with my students.
At this point, I'm more or less certain you'll rarely find situations where you have a mass-appealing context. One students' dream context is another students Most Boring Possible. You're probably better off having many diverse contexts and hit all the MUSIC guidelines (eMpower students, Useful to their long/short term goals, make students Successful, make it situationally and domain-based Interesting, and give people opportunities to demonstrate that they Care about each other).
I say this as someone who grew up in the 90s with my father's Pascal textbook and a deep love for Turbo Pascal.
Regardless, this seems like a nice little document for those 20% of students who are still willing to read supplementary materials. Then again, this is short and clear enough that if it were properly chunked within a course and had graded assignments attached, many students would probably actually skim it.
If you ever want to develop this some more, I hope you'll consider something like Runestone[0], in order to give it some auto-graded questions along the way!
[0] https://runestone.academy/runestone/default/user/login?_next...
Personally, going through OP's site, I was nodding my head and comparing it to what I learned in my undergraduate CS degree. Some of it is dated, but most of it connects to the Architecture and Operating System classes I took.
[0] https://www.acm.org/binaries/content/assets/education/cs2013...
"But in the last 60 years, simply grabbing these dissenters by the lapels and fumigating them with the stinky garlic breath of parenthesized S-expressions has not been a winning strategy. If Lisp partisans want different results in the next 60 years, we need to try something new."
Now, let's make sure we're finding ways that can generalize. It's an important problem in the world today.
Anyway, this kind of experience report would be totally unsuitable for ICER, which is the venue focused on true CS Ed research. This might have a life at SIGCSE, but why go and preach to the choir? And honestly, I don't think it really does merit the level of research publication. This is just a blog post level argument.
I did outline why this site exists. And I do think that this is worth sharing on here, if only because this site drives me nuts sometimes with all its arm chair CS Ed researchers. If I only persuaded a few folks to stop citing HtDP as god's own truth, and to approach that community more critically - I would say that is helpful. Hacker News folks need to understand that education is a heck of a lot more complicated than they probably think it is, and their experiences probably aren't generalized.
I also think that the Racket education community is dying out. For good or bad, I don't think I really have to start publishing research to try and speed it up. But I think that having these reasons and arguments recorded, and written publicly, is a good thing. I am trying to keep in mind, as I write, that some day someone may write some blog posts for "ihateblockpy.com" or "ihatecorgis.com" (my research projects). Perhaps I'll be eating my own words!
But not Haskell. Please don't say Haskell :)
Why does the stability of Racket matter? Isn't the real question more about how easy it is to reuse, readopt, reshare, find, etc. materials? I'll point out that the CSEngageEdu site doesn't have a Racket section. If you want me to find 100 programming problems in Python, I can do so immediately (because I published more than that, and I know others who have published even more). It's a simple fact that there's more community and infrastructure around Racket. There's been some interesting arguments that we shouldn't let that stop us - what about the future? But the reality is that right now, it's harder to teach in Racket, and I don't see any compelling evidence to prop it up further.
> Is there any data about how well the students do following each language choice?
I'm sorry, I had to laugh out loud. You've asked a really reasonable question, but it's one that the CS Ed community bickers about endlessly. I wrote a paper for SIGCSE about trends in what we talk about on the SIGCSE Mailing list. Seriously, every few years we get into the argument. Actual data seems to suggest very little. Heck, it's so hard to compare with all the confounding factors and individualized components that it's probably not really meaningful to get a simple answer. Ultimately? It probably doesn't matter. If you can teach 90% of my students with Racket the way I teach 90% of my students with Python, and you have the time and energy, then that's probably fine. But the simple reality where I'm at is that that's not the case - students who were taking Racket here before I arrived were being traumatized (and I suspect it's true at more places than the Racket folks want to acknowledge). If they don't want Racket, and I can teach a good CS1 in Python or Java or JavaScript, why should I fight that? Language choice doesn't really influence pedagogy as much as we might want to think it does, per this quote from the beautiful Meta paper that came out earlier this year:
> “Given the perennial question of which language, if any, is best suited for the teaching of introductory programming, many papers describe empirical comparisons between languages, often finding no significant difference in learning outcomes, but sometimes finding differences in student satisfaction.”
> “The choice of programming language is clearly a highly subjective one and is driven by many competing factors. It is clear that the literature will continue to host publications making the case for different programming language choices — and that no paper or series of papers will ever put an end to the debate, as no programming language will ever satisfy all of the conflicting requirements of an introductory programming course.”
Yes, so we should look at the relatively more massive amount of research done for languages like Java, Python, etc. SIGCSE and ICER and ITiCSE are full of them. We've learned a lot - learning is hard :)
> Intentionality in the design of a curriculum is better than an ad hoc curriculum.
I strongly agree. I wish I could impart to you how involved I am in Instructional Design with my work. I don't know if this will help, but here's a sample from what I was doing last year: https://acbart.github.io/python-sneks/
> The design recipes give you an excellent foundation for transitioning to a statically-typed programming language with algebraic datatypes.
I'm not clear that that's more than a theory. Even if it's true, is that necessarily the major goal in CS1? Perhaps, but you'll have to convince a few of my colleagues of that.
In general, people learn from presentation of material, participation to demonstrate understanding, and then receiving feedback. They need to be motivated and engaged. If you're asking how I would suggest someone self-learn something, I would suggest that they find a cool project that they're excited by, and then offer resources based on that. Ideally ones with interactive feedback and tons of examples.