Observing a full ISS pass (with binoculars, preferrably) can be pretty interesting, even though ISS passes are such an everyday sight now that I rarely bother to watch anymore. Early in the pass it will appear slightly reddish or orange, because at that time the sunlight is still shining through the solar panels, which contributes a considerable tint to the otherwise still unfavorable phase angle. By the time it reaches the zenith and the phase angle gets more favorable, it will become bright white (especially with a Shuttle docked to it, but not only then). If the pass includes a shadow entry later on, you might want to try and see how long after shadow entry you can still track the station, considering the sun up there of course doesn’t disappear abruptly and the station also may have some external floodlights on. And considering that, during a full overhead pass, its distance to you varies from a few thousand to just about 350-400 miles, you can even tell how its apparent size grows from a “dot” to a “shape” if you follow it the whole time.