My buddy Tom recently emailed to remind me that here in Texas, now is a great time to show your kids the dawn and nightfall shadows on http://www.die.net/earth/hemisphere.html and see how much the shadow is tipped. Then, come back in 3 months and see that the shadow line is exactly vertical at the equinox.
He notes that the other views http://www.die.net/earth/ make it clear the southpole is always light now and the north is always dark.
Cool way to teach your kids that the earth revolved around the sun and not them.
