A teacher or a student, can make use of audio and video files nowadays in class. It's not the first time that one has a video that one downloads from the internet or get it from another kind of resource, but it won't play on his computer! This happens with video files but especially with music, where one encounters several music formats.
Is there a free and open source player which plays practically all types of audio and video files? Yes there is! Just try Smplayer. It is available for windows and linux platforms. If one is looking for help to do the first steps, than one should visit this page. If you want to see how many formats of files are supported, than one should visit this page. The FAQ (Frequently asked questions) section is here. The forum, (the place where people ask all sorts of questions), is here. Enjoy!