In these lectures we will introduce an interactive system that supports writing simple functional programs. Using this system, students learning functional programming: develop their programs incrementally, receive feedback about whether or not they are on the right track, can ask for a hint when they are stuck, see how a complete program is stepwise constructed, and get suggestions about how to refactor their program. The system itself is implemented as a functional program, and uses fundamental concepts such as rewriting, parsing, strategies, program transformations and higher-order combinators such as the fold. We will introduce these concepts, and show how they are used in the implementation of the interactive functional programming tutor.