I think we need to get back to rhyming and memorization at a very early age. I can still, and I know you can too, remember little poems and folktales that set certain presidents and events in my head forever.
My First Grade teacher daughter tried something new in her classroom this past year, to great effect. She had the kids stand behind their chairs and hold on to those chairbacks and dance any which way they wanted while they went through their addition and subtraction tables. Worked like magic, and her kids got the highest scores. They exercised, used self-expression, sang out the numbers until they were set routine, and enjoyed every minute of it!
Bible History picture books have been in proliferation in this country since I was an infant, but you see very few about any other type of history. I think this is a mistake. Start them early, I say! Give them picture books about each president, each war, each state and so on.