There's no penalty for wrong answers. The tutorial is organized so users can quickly learn enough basics to write simple programs, and then expand that knowledge for more complex programs. Thus, discussions on what are variables, the semantics of assignment and ordinary expressions, and so on are glossed over. A different kind of tutorial would be needed for those without such knowledge. Thus syntax diagrams are shown so that the tutorial user can understand it formally enough to actually write legal Ada constructs.
Organization is always a tricky issue for a tutorial.
Naturally, people will learn best if they actually try to build their own programs, but that's not required by this course. Web browsers vary in their capabilities. I've designed Lovelace so that even those with text-only browsers or slow connections can use the tutorial, and those with more capable browsers will see progressively improved results. As a related note, this tutor is designed so that it can be easily extended by others at different locations. Things are designed so that, with a trivial amount of work on the lesson developer's part, users can go from lesson to lesson without noticing that they're working with lessons developed by different people.