YouTube is great, except sometimes you can spend so much time looking for stuff that it becomes a serious time sink. But sometimes you find individuals who you does a really great job in breaking things down and they are a great source to go to for information.
Crash Course video is one that I’ve enjoyed with my kids. The videos are short and enjoyable to watch and has a good amount of content for quick review or introduction to the subjects. If you have a chance, check them out and enjoy some quick learning.