Textbook Entry for Polymorphism Contains short explaination of key concepts for studying reasons. Mostly for me, but anyone taking an APCSA course in their high school is welcome to look over it. Most of the "interactivity" is just for fun. It would likely be easier to just learn the content by looking through the source code, but if it makes you feel cool to input commands into a terminal or something, feel free to open it up elsewhere and read the information out of the terminal.