Go to themeforest. Grab this template http://themeforest.net/item/learning-app-learning-management-system-template/10759166. You might have to add the article function, but you can just suck their blog in and turn it into an article.
Turn it into programatic Craft/twig templates. Challenging, but fun.
You will want https://dukt.net video plugin if you want to see all the available videos in your control panel, otherwise there are generic, free plugins that will allow you to pull outside video in. If you want to stream your own video, then you will know how to pull an RTMP or HTML5 feed in.
If you need to have quizzes, http://barrelstrengthdesign.com has a forms plugin that will handle this quickly. If time is not money, you can make your own plugin to handle that functionality.
If you need to publish a certificate of completion after somebody completes a course https://printmaker.docs.topshelfcraft.com is a plugin that prints from html to pdf - so you design the quiz in a form, validate it as they take the quiz, and if they pass you spit out a certificate. Again, if time is money, this is your solution, if you have all the time in the world, you can create your own custom plugin.