I became a big fan of Planet Nutshell the first time that I saw their series of videos on Internet Safety. Math Shorts is another great series offered by Planet Nutshell.
Math Shorts is a series of 21 animated math video lessons. The majority of the videos are designed for third through eighth grade. Each of the videos has a Common Core standard aligned to it. All of the videos have supporting materials from PBS Learning Media attached to them. The first video in the series is embedded below.
In addition to the math videos and Internet safety videos, Planet Nutshell has also produced great videos on Financial Aid and Climate Science.