Python Practice

Twenty-two short, hands-on Python lessons: start with your first print statement, build up through error handling, generators, classes, and recursion, debug a real traceback, then climb into the code that runs clean and is still wrong. Each lesson gives you a task and a Run button - your code is checked against real tests the moment you run it. Everything runs in your browser.

The last six are the ones that bite at work. A traceback tells you where to look; these do not get you that. A default argument that was built once and remembers the last shopper, a loop that skips items because the list shrank under it, a copy that was never really a copy, a total that is off by a cent because money went through a float, and a capstone where or 0 quietly turns "nobody recorded this" into "this was zero" and drags an average down with it.

Start with lesson 1. You can leave and come back any time - your code is saved locally.