I can shine some light on this since I worked on the project from day 0, before it was even called CMU CS Academy.
The initial vision was to provide a free, online, world class CS curriculum for high school students. What this means is that CS Academy's curricula are designed to be taught in a classroom to high school students. Teachers and their classroom environment were considered as first class citizens in the design, which means a lot of CS Academy's value is its complement of (still totally free) teaching resources and professional development seminars. teachyourselfcs.com et. al. solve a different, but equally important, use case for learners who want to teach themselves CS in a self-paced fashion. CS Academy chose to attack the high school CS curriculum because there was (and still is) a clear lack of world class solutions, and we felt we were best suited to take on that particular challenge.
That being said, according to some of the comments, it sounds like there are workarounds to sign up as a Mentor if you just want to play around with some of it.
Disclaimer that these are my opinions only, and not those of CMU/CMU CS Academy. I am no longer actively working on the project.
The initial vision was to provide a free, online, world class CS curriculum for high school students. What this means is that CS Academy's curricula are designed to be taught in a classroom to high school students. Teachers and their classroom environment were considered as first class citizens in the design, which means a lot of CS Academy's value is its complement of (still totally free) teaching resources and professional development seminars. teachyourselfcs.com et. al. solve a different, but equally important, use case for learners who want to teach themselves CS in a self-paced fashion. CS Academy chose to attack the high school CS curriculum because there was (and still is) a clear lack of world class solutions, and we felt we were best suited to take on that particular challenge.
That being said, according to some of the comments, it sounds like there are workarounds to sign up as a Mentor if you just want to play around with some of it.
Disclaimer that these are my opinions only, and not those of CMU/CMU CS Academy. I am no longer actively working on the project.