The content seems good but I'm not a fan of the way the sections are laid out on the introduction page. The courses should at the very least have hyperlinks for each of the learning objectives.
I actually prefer the way it is. When there are too many links around, I tend to do some DFS-like reading and it ends up anxiety and tons of tabs. Things get worst when there're loops.
There's a lesson overview on the left-side navigation, and an inner-lesson table of contents on the right-side navigation, which links to each topic or learning objective.
If you're on a narrow format it looks like that table of contents is set into the top of the article below the lesson title.