Some new content was added to the Codecademy Alex Skills course - see this announcement from 26th Oct: https://developer.amazon.com/blogs/alexa/post/3ce5b1e9-b966-4f87-b703-9ea2125fa454/introducing-new-advanced-alexa-skills-courses-by-codecademy
But, as of time of typing, there are problems.
For example, the instructions and test window for Q6 and 7 are the wrong way round, and at the end, even if using their "correct" code, it doesn't actually work. There are typos and confusingly worded instructions. The videos are MASSIVE in terms of download size for what they are (148Mb for 90 seconds?! won't play on 4Mb broadband), and one of them just goes off on a completely different tangent, nothing to do with the instructions or what it's supposed to be showing.
The original basic course itself was great, and I'm sure this will be too, but I just found (and reported) my 7th issue with this new course, so I'm going to take a pause there - it's just not ready yet.