I'll add one more item to this list: Python has a turtle graphics library out of the box. Turtle graphics is an excellent way to explain concepts like loops, functions and recursion in a visual way that is much easier to grok than the more abstract explanations. It goes step by step, too: you can show the basic notion of issuing statements by drawing stuff like triangles and squares and pentagons; then demonstrate how this becomes tedious as number of edges grows, which gives an opportunity to introduce looping; then show how it's essentially the same loop for various polygons with different parameters, and introduce functions. Drawing spirals, snowflakes and trees is where recursion steps in. And so on.