'Invigilating' is one of those fantastic British terms, like 'knackered' or 'headmistress' or 'moggie'. It implies keeping a vigil, which, actually, is pretty much what it means. Better than the American equivalent, 'proctoring', which conjures images of a much less pleasant nature.
Yesterday, tomorrow, and a week from Monday I'm invigilating an examination of sorts. Not anything you as a spectator will be tested on, but rather an art exhibition. My job is to keep an eye on the artworks, try to prevent small children from destroying them, that sort of thing. (I've already failed on that front - a teeny wee Finn raced over and yanked a bit off before his mother could translate my yell not to touch the artwork.)
And in a sense, you might feel like you're being examined, because if you enter the room I'm likely to swoop upon you with a questionnaire, asking you to fill it out front and back. You won't be graded on it, of course - but the artist and her research collaborators will be. If the public likes it, the funders will be happy with the artist and the research team, and everyone will be happy. If the public doesn't like it... well, so far, it's a success, so no need to worry about that.
Still, though. I'm 'invigilating'! Keeping a vigil with five interactive light sculptures in the keep of an umpteenth century castle. If you're around, come have a look!