I really enjoyed your "hour of code" sequence with videos. Very well done!

This task has a problem:
https://app.code-it-studio.de/course/step/12/131

The task asks the student to change the background to a random color 30 times a second. High contrast flashing areas at 30fps can be dangerous for photosensitive people -- I'd recommend either dropping the background fill or dropping the framerate to 4/fps.

https://developer.mozilla.org/en-US/docs/Web/Accessibility/Seizure_disorders