After years of experimentation, online teaching has gone through a phase transition with the appearance of massive open online courses (MOOCs), following the model pioneered by Salman Khan with short videos and the use of tablets. Dozens of university-level courses are now available, and followed by hundreds of thousands of online students. We report on early experiences with teaching “Fundamentals of Electrical Engineering” and “Digital Signal Processing” on an open online platform (Coursera). We address in particular: (i) suitability of online platforms for signal processing oriented topics; (ii) structuring of material for the online format; (iii) quizzes and exercises for large classes; (iv) grading methods and possible certification issues; (v) learning from teaching, forums, and data mining of students feedback.