From Kim's excellent blog:
This seems to be the most difficult concept for most adults to grasp. Surely there must be a correct order in which to teach history? Nope. I tell you truthfully. Nope. If you are skeptical then order catalogs from several major publishers and compare the scope and sequence of each. You will discover that one begins with the beginning of time in grade one and moves forward in strict chronological order each grade. Another will begin with local and family history and move outward to more abstract information. Others begin with American history and give world and ancient histories a nod in junior high. All will assert that their way is critical to success and may even suggest that failing to adhere to their system will lead to disaster. This is just not so.