OK, here is a quickie reference link today, for all the teachers out there: Netstate.com. A website with basic information about all of the states, including the year it became a state, where the name came from, and the various nicknames. If you click on the links in the sidebar, you can find even more interesting facts. For example, did you know that the official cooking vessel of Arkansas is the Dutch Oven? Or that the square dance is the official dance of both Washington and Arkansas (and, I feel sure, at least a couple other states...must be a strong square dance lobby out there). The facts have some sources included, so you can go find more information, or at least be sure your students are getting real information.
Addendum: There is a strong square dance lobby out there! At one point they were trying to get the square dance to be the state dance for all of the states! It's on this website, if you look for it.