Problem Set 0

What to Do

  1. Download and install the latest version of Chrome, if you don’t have it already.
  2. Implement your very own Scratch project using Chrome, per this specification.

When to Do It

By 11:59pm on Sun 9/8. If you add the course after then, no worries, email for an extension.

How to Get Help


Here are David’s examples from lecture if you’d like to review! To see the source code of each, click See inside.

How to Submit

Step 1 of 2

Submit this form.

If it “looks like something went wrong,” try using your browser’s incognito or private mode instead.

Step 2 of 2

This step assumes that you’ve downloaded your Scratch project as a file whose name ends in .sb3. And this step also assumes that you’ve signed up for a GitHub account, per the above form.

  1. Visit this link, log in with your GitHub account, and click Authorize cs50.
  2. Check the box indicating that you’d like to grant course staff access to your submissions, and click Join course.
  3. Go to
  4. Click “Choose File” and choose your .sb3 file. Click Submit.
  5. Visit, logging in with your HarvardKey and then your GitHub account. You should see (after a minute or two) your submission and your scores! Click the submission link and then the check50 link to see which requirements your project met. You are welcome to resubmit as many times as you’d like (before the deadline)!

These were quite a few steps, so if you have any trouble, not to worry! Email before the deadline, and we’ll lend a hand!