A student sitting through a boring class glances over at a friend and rolls her eyes. what would erving goffman call this?

Erving Goffman would call this "backstage".

One of Erving Goffman's insights is the degree to which individuals take part in introductions of self. Front-stage conduct is the show implied for 'public' utilization: clever, urbane, unsafe, keen, smooth, rational, scholarly etc. This relies upon the gathering of people, obviously, and it is intended to make oneself look great. Backstage conduct is nearer to the genuine self, less varnished, less a demonstration.

Expression of Behaviour

Explanation:

Erving Goffman was one of the most notorious sociologists and his model is usually referred to as the dramaturgical model.

Goffman says that we create impressions through sign vehicles which includes both our language as well as our body language. We also create impressions by our expressions.

In this question, a student rolls her eyes glancing over a friend, so this would be an example of expression of behaviour (specifically body language)