It is a while I don't code in elixir however when I was learning the complex part definitely wasn't the one in this course.

The complex part is to start to think about decompose a big problem into smaller problems solvable by different Erlang modules. When to spawn another process or when to re architecture the code.

Really great work but I would go a little bit ahead and add some more specific Elixir/Erlang part.

Also what really really helped me was to understand how a GenServer was written, it may be worthed to make the student write its own limited version of a GenServer...