I remember my global studies teacher using the Animaniacs world song. It's a little out dated but it is still catchy. First she played it through and just let the kids listen to it. The next time they had to start coping down the countries in the song. Then they had to start signing along. Basically by a certain point each student had to have it memorized. I was a senior when she started this with the younger class but I still love the song and have the first part memorized to this day.