Project 9: Building from Scratch

When to Do It

By 2025-12-31T23:59:00-05:00.

What to Do

Visit scratch.mit.edu and sign in to your account. Click the “Create” button to create a new project.

Your assignment is to create a new Scratch project that uses all of the ideas you’ve learned in the course. Your project should include all of the following:

At least three different sprites.
At least three total backdrops.
At least one broadcast.
At least one clone.
At least one custom block.
At least one variable.
At least one loop.
At least one condition.
At least one event.

If any of the above nine requirements are missing, your project will not pass, so make sure they’re all present!

Once finished with your project, select File > Save now one last time. Then select File > Save to your computer and keep that file (with file extension .sb3) so that you can submit it. If prompted by your computer to Open or Save the file, be sure to Save it.

How to Submit

Beginning 2024-01-01T00:00:00-05:00, the course has transitioned to a new submission platform. If you had not completed CS50 Scratch prior to that time, you must join the new course pursuant to Step 1, below, and also must resubmit all of your past projects using the new submission slugs to import their scores. We apologize for the inconvenience, but hope you feel that access to rapid grading, which is new for 2024, is a worthwhile trade-off for it, here!

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.

Visit this link, log in with your GitHub account, and click Authorize cs50.
Check the box indicating that you’d like to grant course staff access to your submissions, and click Join course.
Go to submit.cs50.io/upload/cs50/problems/2024/scratch/build.
Click “Choose File” and choose your .sb3 file. Click Submit.

If you encounter the error “No files in this directory are expected by cs50/problems/2024/scratch/build”, please make sure your scratch project file name indeed ends with .sb3!

That’s it! Once your submission uploads, you should be redirected to your submission page. 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)! Note that if you upload a file whose size is larger than 10MB (which is quite large for a Scratch project) check50 may struggle to process it. Best to make sure your file is smaller than that limit.

To view your current progress in the course, visit the course gradebook at cs50.me/cs50s!