Second, measures your keystroke dynamics and collects comprehensive typing statistics. For example, it measures your typing speed for each individual key, and uses this data to generate random words putting emphasis on the weakest key. The more troubles you have with a particular key, the more you will be  typing it. It means, the generating algorithm will put that letter in every word in the next generated lesson. Your typing skills are re-evaluated after every completed lesson, and the next lesson will be adjusted accordingly.
With your index fingers you can feel a bump on the keys 'F' and 'J'. When you type you must get back to these two keys as soon as a key has been pressed on the keyboard so that you know all the time where you are on the keyboard. If you don't find the keys 'F' and 'J' again you will get lost and make a lot of mistakes. For the same reasons the first lessons are done without ever moving your fingers from these two keys.
EdX is another leading online-learning platform that is open source instead of for-profit. It was founded by Harvard University and MIT in 2012, so you know that you’ll learn about cutting-edge technologies and theories. Today, edX includes 53 schools. You probably can’t go wrong with the free Introduction to Computer Science from Harvard University.