@WBYeats,
WB: If a student is sitting at table, facing a professor, whom he knows to be teaching engineering, but not exactly which kind of engineering in the engineering faculty, how should he phrase the question? Can this?:
-Which department are you working in/with/at?
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... working in?
working with? might entail some collaborative effort but it could also work in CONTEXT with a professor who moves around quite a bit, sort of in the same vein as "Who are you working with now?"
Which (location/building) are you working at?