Advanced Balloon Animals
Object oriented programming is a bit like making balloon animals - you start with a blob, and by imposing a template on it, induce a behavior that causes pleasure.
(Yeah, that's a bit of a stretch, but the title was sort of handed to me.)
To write a useful module in Drupal 8, you need to be able to manage some basics of object oriented programming. Let's build a module together and see if we end up with a giraffe, or if a loud noise and a scrap of rubber.
(Happily, as with balloons, you can always start over again.)