I had a second grade teacher ask me to help find a computer lab activity for her kids related to the states of matter.
I came up with a lesson using Brain Pop Junior (free for South Carolina teachers through Discus) but I also found this Study Jams site through Scholastic. I watched the Solids, Liquids, and Gas one and that was pretty good. I really liked the song that went with it (although I wasn't a huge fan with how long it took to load).
They also have a Water Cycle video as well (which sadly doesn't have a song :)
I wish they had more videos but they only have two math ones (fractions and determine the missing operation).