How open source improves a developer skills ?

There is an abandoned treasure for every developer. But I discovered it, worked hard on it and the benifits from is very huge. It's an open source contribution. Any developer needs to improve his skills and upgrade them but he don't know how ? reading books ? learning a new techenology ? new language ? so a lot of resources which make the dicision more diffcult. The solution is write any idea (micro framework, simple game, template engine, small package, etc…) and you will learn more than you imagine, you will find yourself searching a lot and it makes you decide what will you need to learn and how. Also that makes you write a code everyday and read a code reguaraly so it will improve your code skills, your reading skill become better because you knew what you need to read and which book to pick. Just block One hour or Two to work on your own application and I promise the results will be amazing! . Open Github then create a new repository without a lot of thinking and start coding, refactor your code, invite your friends or coworkers to review your code and to help you to fix your mistake. Thanks for reading