Sigma observed the commotion going on around the room as what was once progress regressed in to accusations, bad plans, and claims of not caring. "I need to regain control of the situation." Sigma thought to himself.
"All right, first off, allow me to say this:" Sigma started. "The plan of introducing ourselves isn't going to work for the obvious reason that the teacher can easily fake a name. With a roll call sheet, assuming everypony in the class is present, we'll be able to call everyone to roll and pick out the pony who's name wasn't called, who will be the teacher. If the teacher tries to impersonate one of the other students while everypony is present, the actual student will call her out. However, if it turns out that someone is absent..." (Sigma thought for a moment.) "We'll just have to formulate a new plan." "Now!" Sigma yelled authoritatively. "Everypony, go look for a roll call sheet as well as a key, except for one of you..." the white unicorn muttered.
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Sigma turned to the bad-mouthing stallion, and stomped his hoof in an attempt to wake him up. "I'd imagine an impolite, carefree individual such as yourself would know a thing or two about picking locks." Sigma mused. "If you successfully pick the lock to the other room, then you'll help our chances of finding the roll call sheet."