First off, fyi, cis isn't an acronym.

This can honestly be kinda hard because there aren't a lot of nongendered terms for this, and those that do exist would definitely feel othering in this context (in the same way that being the only person asked your pronouns in like a larger introductory context is othering). My thought would be to just use some (neutral! Be careful about that part!) physical descriptions, like "excuse me, student with the black hair". Otherwise, maybe you can make a loud noise (e.g. drop a textbook on your desk) and then get that person's attention specifically when they (and others) look? Otherwise physically go over and tap their shoulder.

None of those solutions are perfect and all of them are obviously contextual, but it's what I got