Location, location, location. True in real estate, and even more so in chemistry class. A student at Glasgow High School in Kentucky decided to roll video to point out that his teacher's demonstration of the wonders of natural gas was leaving ugly black marks on the classroom's ceiling. What neither teacher nor student seemed to notice was that sprinkler head up there. And what happens when fire licks the sensors of a sprinkler system, class? Bueller? Anyone? Well, you know the drill. Principal Keith Hale said "the kids did a good job" of evacuation, though he obviously didn't go to the video to hear the cameraman crow about all the YouTube hits he expected.