This is a great project for G+T students in fifth and sixth grade. Variations I have done include working individually and letting the students choose anywhere in the world they would like their country to be. The geography and climate of their portion of the earth affects the other aspects, such as history, customs, foods, etc.
Need some social studies project ideas? Learn how to make Social Studies more engaging for your students with inquiry circles. Inquiry circles reinforce social studies standards while teaching the research process. (Grab the free social studies project worksheet)