Can't stress the importance of a REPL enough. The hands-on interactivity, call and response, and introspection pushes your understanding of the language (and ability to build out astounding new ideas) so much more quickly. Also love that he highlighted Logo and Basic, which is exactly how I learned programming. The former in elementary school computer labs, the latter as a young kid on the family's 386, eager to make my own version of Nibbles.