Book
Links to the repository and documentation for the Karel the Robot unit.
The book is Karel J Robot: “A Gentle Introduction to the Art of Object-Oriented Programming in Java”, by Joseph Bergin, Mark Stehlik, Jim Roberts, and Rich Pattis. We have the January 2008 printing, but all versions are very similar. Happily, the book is available for under $10 used if you want one or want to donate one.