It’s a word that I didn’t learn until a professor of mine at Hampshire College wrote it in an evaluation of my Division II work (which was very gratifying), so maybe high schoolers need not learn it. If you think they should, though, then here is a context clues worksheet on the adjective perspicacious. It means “of acute mental vision or discernment.”
If you find typos in this document, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.