Problem Set 0: Scratch

This course’s philosophy on academic honesty is best stated as "be reasonable." The course recognizes that interactions with classmates and others can facilitate mastery of the course’s material. However, there remains a line between enlisting the help of another and submitting the work of another. This policy characterizes both sides of that line.

The essence of all work that you submit to this course must be your own. Collaboration on problem sets is not permitted except to the extent that you may ask classmates and others for help so long as that help does not reduce to another doing your work for you. Generally speaking, when asking for help, you may show your code to others, but you may not view theirs, so long as you and they respect this policy’s other constraints. Collaboration on quizzes is not permitted at all. Collaboration on the course’s final project is permitted to the extent prescribed by its specification.

Below are rules of thumb that (inexhaustively) characterize acts that the course considers reasonable and not reasonable. If in doubt as to whether some act is reasonable, do not commit it until you solicit and receive approval in writing from the course’s heads. Acts considered not reasonable by the course are handled harshly. If the course refers some matter to the Administrative Board and the outcome is Admonish, Probation, Requirement to Withdraw, or Recommendation to Dismiss, the course reserves the right to impose local sanctions on top of that outcome that may include an unsatisfactory or failing grade for work submitted or for the course itself.

If you commit some act that is not reasonable but bring it to the attention of the course’s heads within 72 hours, the course may impose local sanctions that may include an unsatisfactory or failing grade for work submitted, but the course will not refer the matter to the Administrative Board.

Your work on this problem set will be evaluated along two axes primarily.

All students, whether taking the course SAT/UNS or for a letter grade, must ordinarily submit this and all other problem sets to be eligible for a satisfactory grade unless granted an exception in writing by the course’s heads.

First curl up with Nate’s short on binary, if not too familiar:

And next with Nate’s short on ASCII:

Consider these questions rhetorical for now, but odds are they’ll come up again! Not to worry if the answers aren’t obvious at first. They’re meant to induce a bit of thought! Week 0’s first lecture and Nate’s videos should provide you with the building blocks (daresay inputs!) with which to solve these problems.

Incidentally, ever wonder what that big machine is by the stairs in the Science Center? It’s the Harvard Mark I, one of the world’s earliest (electro-mechanical) computers, whose purpose was, well, to compute (albeit slowly by today’s standards)! You might enjoy this tour by Prof. Harry Lewis:

Head to http://scratch.mit.edu/ and sign up for an account on MIT’s website by clicking Join Scratch atop the page. Any username (that’s available) is fine, but take care to remember it and your choice of password.

Then head to http://scratch.mit.edu/help/ and take note of the resources available to you before you dive into Scratch itself. In particular, you might want to skim the Getting Started Guide.

Next head to http://scratch.mit.edu/projects/26329354/ to see Pikachu’s Pastry Catch by Gabe Walker. Click the blue square above the game’s top-left corner if you’d like to full-screen the user interface (UI). Then click the green flag. Per Gabe’s instructions, as soon as you hit your keyboard’s space bar, the game will begin! Feel free to procrastinate a bit. And if you’d like to try out Ivy’s Hardest Game, by Carlos Peña-Lobel, head to http://scratch.mit.edu/projects/26329347/.

If you’ve no experience (or comfort) whatsoever with programming, rest assured that Gabe’s and Carlos’s projects are more complex than what we expect for this first problem set. (Click See inside in Scratch’s top-right corner to look at each project’s underlying "implementation details.") But they do reveal what you can do with Scratch.

In fact, for a gentler introduction to Scratch (and programming more generally), you might want to review some of the examples that we looked at in Week 0’s second lecture and take a look at a few more, the "source code" for which can be found at http://scratch.mit.edu/studios/522341/. Allow me to take you on a tour, though feel free to forge ahead on your own if you’d prefer:

And you might also want to watch Allison’s short on Scratch:

Feel free to download the source code for a few more projects from http://scratch.mit.edu/explore/projects/all/ or elsewhere. For each program, run it to see how it works overall and then look over its scripts to understand how it works underneath the hood. Feel free to make changes to scripts and observe the effects. Once you can say to yourself, "Okay, I think I get this," you’re ready to proceed.

Now it’s time to choose your own adventure! Your mission is, quite simply, to have fun with Scratch and implement a project of your choice (be it an animation, a game, interactive art, or anything else), subject only to the following requirements.

Feel free to peruse additional projects online for inspiration, but your own project should not be terribly similar to any of them. Try to think of an idea on your own, and then set out to implement it. But don’t try to implement the entirety of your project all at once: pluck off one piece at a time. Gabe, for instance, probably implemented just one pastry first, before he moved onto the game’s other sprites. And Carlos probably implemented Yale before he moved on to implementing MIT. In other words, take baby steps: write a bit of code (i.e., drag and drop a few puzzle pieces), test, write a bit more, test, and so forth.

If, along the way, you find it too difficult to implement some feature, try not to fret; alter your design or work around the problem. If you set out to implement an idea that you find fun, you should not find it hard to satisfy this problem set’s requirements.

Alright, off you go. Make us proud!

Not quite sure how to begin? Feeling a bit overwhelmed? Not to worry. Join Zamyla for a walkthrough of this problem set, if you’d like more of a tour:

Incidentally, if you don’t have the best Internet access, you’re welcome to download Scratch’s "offline editor" (which I used in Week 0’s second lecture) at http://scratch.mit.edu/scratch2download/. But when done with your project offline, be sure to upload it to your account at http://scratch.mit.edu/ via File > Share to website in the offline editor.

Once finished with your project, click See project page in Scratch’s top-right corner. Ensure your project has a title (in Scratch’s top-left corner), some instructions (in Scratch’s top-right corner), and some notes and/or credits (in Scratch’s bottom-right corner). Then click Share in Scratch’s top-right corner so that others (e.g., your TF!) can see your project. Finally, take note of the URL in your browser’s address bar. That’s your project’s URL on MIT’s website, and you’ll need to know it later.

Oh, and if you’d like to exhibit your project in Fall 2014’s studio, head to http://scratch.mit.edu/studios/522331, then click Add projects, and paste in your own project’s URL.

Incidentally, if curious to learn more about the design of Scratch itself, you might like this segment with our friends from MIT’s Media Lab:

To submit this problem set, visit https://forms.cs50.net/2014/fall/psets/0/. You’ll find that a few questions await. Be extra-sure that your answers are correct, particularly your project’s URL on MIT’s website, lest we overlook your submission!

CS50 collects quite a bit of data for research purposes. Please forgive the length of this first problem set’s form! In total, the form will probably take 30 or more minutes to fill out. Not to worry if you finish shortly after the problem set’s deadline, so long as you start before the deadline. Future problem sets' forms will be much quicker!

This was Problem Set 0.