Other students arrived, in groups and singlets (mostly Ravenclaws). Harry, however, was listening. He heard the sound of construction, of metal flexing, of wood bending, slamming sounds, banging sounds. It was a cacaphony of what sounded like distant sounds.
Had Snape partially silenced what he was doing?
He must have, or else how would it all sound so far off? Harry certainly didn't know a spell for partially silencing an area - although he immediately coveted the spell. It would be useful to have someone accidentally overhear something - because wasn't something nearly-silenced an indicator that it was something juicy? Harry badly wanted it just to screw with the gossips' heads, and then he'd go and do something useful with it, surely he could manage that. There were so many things one could do with a good 'miscast silencing spell' - enticing Rita Skeeter into a volcano, for example!
A veritable world of possibilities!
Snape stood, out of invisibility now, and a considerable portion of the students jumped. Perhaps they'd failed to notice how the Defense doors were shut. Snape always kept the doors shut while he was inside, and always left them open otherwise. At least with Gryffindors in the room. Harry thought, understanding that Snape may have wanted his keen ears to notice any possible impending mischief or mayhem.
"Today, your grade will be entirely contingent on your punctuality, and speed is of the essence." Snape sneered. Then he gestured, and Harry's jaw dropped. Snape had made... something that looked suspiciously like a jungle gym - with style. It had gone quite Gothic, you see, and Harry wanted to giggle at the thought, but ruthlessly held himself quiet. Seriously, a jungle gym with gargoyles!
Snape sneered, and called out, "Sue Li!" The first girl was off - her Asian physique had her slipping and sliding through the course. Harry wondered how she knew where to go, but figured that Snape would have told them if it wasn't obvious.
"3:54" Snape sneered, "Crabbe, you're next."
By then, Harry had caught the pattern - choose the weakest students first, strongest last.
Crabbe had a lot more difficulty getting through the course - there were places where he had to squeeze - and the metal squealed, shook, and didn't look as good - the wood actively swayed under him as well.
Goyle was next - and by then, the structure was starting to suffer some structural difficulties. To wit, some parts were starting to separate from others - Harry didn't think it could stand another heavyset person - and Millicent hadn't gone yet.
Harry swallowed, thinking, How much worse is it going to be by the time it's my turn?
[a/n: Yes, Harry, its called performance-based testing. You get a harder course because you have a better grade in the class. Reviews?]