There is a "typo" in the instructions:
Don't forget to click the "Check My Work" button when you think you have it right.
There is only the "submit" button.
Also, it would be nice if the grave accents (backticks) were on the same line as in the video/slide, since they are kind of hard to see due to the opacity(?) setting.
moderator: Just confirming this is the case, and sorry about the error. At the moment, we aren't making anything other than critical changes, but if this changes this should be something I can easily fix up. Thanks for reporting this.