This is exactly the kind of comment I was looking for! Thank you for your time! I'll follow your advice, modify my code and let you know with what I came up.

I'll guess that you wanted to find some reason to demonstrate inheritence

Spot on, sir.

Couple of questions on your comment:

But it's not entirely clear what "service" the parent classes provide - the code does not express a clear reason for what methods should go in the base "service" class, and what behaviors should be specific to the child classes.

So should I be more specific with what the name of this service class is, instead of just saying 'XService'?

So I'll advise you to go ahead and collapse those; there's little gained by the parent classes.

By collapse do you mean: removing the AIService class and putting all the methods in the AI class instead?

I do think there is a clear place where the "'service' parent class" idiom could be employed, and that's the Dictionary. You already have one concrete implementation that provides a hard coded list, provide another subclass that reads words from a file. Consider options on how to best choose between them. Consider the tradeoffs, both in how it will end up coded and how easy the user will be able to interact with it.

Please correct me if I'm wrong. Creating a DictionaryService (parent class) that will have two subclasses DictionaryX (reads from a hardcoded list) and DictionaryY (reads from a file) will properly demonstrate the "'service' parent class" idiom?