pybasictraining is a set of challenges that I put together a few years ago as a different mechanism to teach students python. I've had good feedback so far, and I think it's been fairly useful.
I've modified pybasictraining so that students can run and complete it in a web-based environment, without needing to install any special dependencies or anything. Unfortunately, you can't save anything right now, but maybe that will get addressed in the future.
http://mybinder.org/repo/virtuald/pybasictraining
Students and Mentors -- please visit the notebook and try it out, and give me your feedback so we can make it easier to use, and maybe have better documentation and more challenges for students to complete.
If you want to play with the source code, check out
https://github.com/virtuald/pybasictraining