If you've never seen the classic short "Powers of Ten," I've got a treat for you. Created in 1968 for IBM by Charles and Ray Eames (yes, of Eames Chair fame), the film has a very simple premise: start at a static scene, then start zooming out, at one "power of ten" per ten seconds -- for example, from 102 meters to 103 meters. As we zoom out, we see the earth, the solar system, the galaxy, and so forth. Once we reach 1024 meters (the size of the observable universe), the camera then begins a faster zoom-in...and goes beyond the original scene, into the microscopic scale and beyond.
For me, "Powers of Ten" is an educational touchstone -- it's a film I was shown several times in science classrooms, and to this day, I find it captivating in its simplicity and power. All you do is zoom way out and zoom way in -- the universe is just a matter of perspective.
(Thanks to Kottke.org for pointing to this YouTube clip!)