Mighty Book

http://www.mightybook.com/

This is a site with books, games, songs, etc. Some are free but more are available with a subscription.

This site has numerous games, interactives and printables to help enhance and practice elementary skills in Math, Science and Language Arts.

VocabAhead

This is a great site that has video to explain vocabulary. It also has a place to sign up to receive the word of the day which sends you a vocabulary video each day.

Here is the link: http://www.vocabahead.com/