Free online course :coursera

 coursera.org is a organizing lessons online

 this text is part of site's about:

We are a social entrepreneurship company that partners with the top universities in the world to offer courses online for anyone to take, for free. We envision a future where the top universities are educating not only thousands of students, but millions. Our technology enables the best professors to teach tens or hundreds of thousands of students.
Through this, we hope to give everyone access to the world-class education that has so far been available only to a select few. We want to empower people with education that will improve their lives, the lives of their families, and the communities they live in.

Classes offered on Coursera are designed to help you master the material. When you take one of our classes, you will watch lectures taught by world-class professors, learn at your own pace, test your knowledge, and reinforce concepts through interactive exercises. When you join one of our classes, you'll also join a global community of thousands of students learning alongside you. We know that your life is busy, and that you have many commitments on your time. Thus, our courses are designed based on sound pedagogical foundations, to help you master new concepts quickly and effectively. Key ideas include mastery learning, to make sure that you have multiple attempts to demonstrate your new knowledge; using interactivity, to ensure student engagement and to assist long-term retention; and providing frequent feedback, so that you can monitor your own progress, and know when you've really mastered the material.
We offer courses in a wide range of topics, spanning the Humanities, Medicine, Biology, Social Sciences, Mathematics, Business, Computer Science, and many others. Whether you're looking to improve your resume, advance your career, or just learn more and expand your knowledge, we hope there will be multiple courses that you find interesting.

Runs Python programs in your browser

CodeSkulptor runs Python programs in your browser
CodeSkulptor runs in Chrome 18+, Firefox 11+, and Safari 6+.Some features may work in other browsers, but do not expect. full functionality.  It does NOT run in Internet Explorer.
http://www.codeskulptor.org/