If a student raises a hand to speak in class, the person is using a

Raising a hand to signal a wish to speak is an emblem, a gesture with a fixed shared meaning that can replace words.

Emblems are understood the same way within a culture and translate directly into a verbal message.

A modifier is not the recognised non-verbal category for such a direct sign.

A regulator manages the flow of conversation, like a nod that keeps a speaker going, rather than standing for a full message.

A display, as in an affect display, shows emotion on the face and is not this deliberate coded signal.

Emblems are the non-verbal signs closest to language.