This application started out as a personal experiment to learn and become more familiar with Rails. The original intent was to build out an application to assist students learning the Japanese language, and thus much of the original functionality and models are focused around the language and building a framework for disciplined study of the language.
After working on the project for a while, quite a bit of tangentially related functionality ended up getting thrown into the overall app, which at present can definitely use a major refactor; however, the app includes a functional flashcard and deck system that is on its way to becoming a full-fledged application on its own. The Japanese-related classes and modules in app/lib/japanese feature some interesting, though verbose, code for working with the Japanese language. Tests covering what exactly those modules do can be found in /spec/models/word_spec.rb.
The /stan_algorithms folder includes a set of algorithms that are completely unrelated to the app, but were just exercises to build fluency with the Ruby language itself.