Teach by Example is a common Instant card from Strixhaven: School of Mages (STX), collector number 241. Current market price: $0.23 (foil $0.27), TCGplayer market prices via Scryfall.
({U/R} can be paid with either {U} or {R}.) When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.