1. To look at someone, or to look someone up and down, often in order to make a judgement about them. Idiomatic English = size someone up.
2. To consider a student and their work in order to make a judgement about the quality of their work. English = assess.
3. To stare at someone, especially in a way that indicates a sexual interest. Used showing disapproval. English = ogle. Informal English = perve, have a perve, gawk at.
4. [With a negative facial expression] to look at someone as if you think that they have very little value or importance; to look at someone with a feeling of dislike and rejection. English = scorn, disdain. Idiomatic English = look down your nose at someone.