MOOC Review: CS50 Introduction to Computer Science

Course Title: CS50 Introduction to Computer Science
Provider: Harvard via edX
Price: Free
Level: Introductory
Effort: 10 – 20 hours per problem set, 9 problem sets and a final, self-paced
Prerequisites: None
Completion awards: Verified Certificate available for USD$90

About the course:
A lot of people view this course as the gold standard in introductory computer science MOOCs.  Having been through it now, I’m afraid I have to disagree.  It is an amazing course, though, and the one best placed to get you into the middle of useful coding as quickly as possible.

The structure of the course follows what you might expect of a university course translated to an online MOOC: each week has a very, very long lecture, followed by shorter bits from teaching assistants highlighting important concepts, and then there’s a problem set which is a series of challenges which ostensibly can be solved using the techniques introduced that week.  There is an exponential increase in difficulty from week to week, because both the material covered is more difficult, and the amount of documentation relating to solving the challenges is reduced.  This is meant to foster habits of independent study to resolve such challenges in the future.

This structure is the first relative weakness of the course.  (Relative to the MIT CS introduction course using Python.)  The MIT course imagines education looking more like the web.  The Harvard course spends countless resources trying to make the web ape its own institution.

As a former trainer, the most important thing about educating people is keeping them awake and interested long enough to learn, so it’s really about entertaining.  The lecturer, Professor David Malan, is extremely entertaining on stage.  The format is fundamentally outdated, however.  There could be a hundred clips where there’s currently a 105 minute video, each collated, indexed, and cross-referenced.  A build-your-own lecture series could take the place of an impending Sander’s Hall nap.  MIT did this beautifully in their latest foray into CS as a MOOC.

The languages “taught” are fantastic.  They start by giving a few rules-of-thumb in Scratch, and pretend that they’ve therefore taught it.  They next spend several weeks on C, and this is an impressive tutorial for the language … for any language.  They then give a small grounding in Python, and then a cheat sheet for SQL, JavaScript, and maybe a few others.  Really, I think they’d do better by having a hard limit on two languages, because everything beyond Python was literally worse than having no experience at all.  Students are expected to meaningfully interact with those other languages, without sufficient preparation.  In solving PSets, students already know those topics, or they luck into trying the correct technique the first time, or they end up chasing their own tails for hours and hours before giving up and asking on a public forum for help.  I spent many hours answering questions in the CS50 subreddit to alleviate some of the pain of such students.  (An example is that they expect students to use object-oriented programming techniques, but never discuss what an object is, let alone what object-oriented programming is.)

I would disagree that it is an introductory module.  It may be introductory if you’re on campus at Harvard, and can stop in and chat to a staff member for twenty minutes, and you’re literally spreading this across a third of a year.  If you’re doing this on your own, you’re going to have to come with a pretty strong intuition of why computer programs don’t do what you expect, and how to troubleshoot to figure out where it all went a bit wrong.  (The tool created to understand this in C is fantastic.  Because of this, they don’t teach how to figure out how to do it when learning C, and therefore students have no concept of basic troubleshooting techniques once the module moves away from C and that tool is no longer available.)

If you survive through to the victory lap of the final (which is really just whatever personal project you want to make a video for), you’ll be ready to take on any formal CS education.  I doubt you’ll be prepared for properly undertaking independent study, however, because the theory behind the coding is often ignored.

The real time I put into this was between 4 and 12 hours per PSet (typically on the lower side), so maybe 60 hours, plus another two hours each “week” watching lectures.

I’d recommend people interested in CS and coding take this module … but only if they also undertake the MIT or UBC introductory modules.

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