Free books, simulations, tools and reference sheets, chosen and shared by teachers and learners. Pick a subject and a level to see what is there.
Hundreds of example graphs with their code. Find one that looks like what you want, and change the numbers.
Paste a program, and watch it run one line at a time, with the variables drawn as boxes. Excellent when a loop or a function is not clear.
A free book of small, useful programs: working with text, files, spreadsheets and the web. Good once you finish Essentials.
A friendly book that teaches programming as a way of thinking, with many exercises. Free to read online.
The official tutorial, written by the people who make Python. Read it after the Foundations chapters, as a second voice.