First Day of Class is a common Instant card from Strixhaven: School of Mages (STX), collector number 102. Current market price: $0.21 (foil $0.39), TCGplayer market prices via Scryfall.
Whenever a creature you control enters this turn, put a +1/+1 counter on it and it gains haste until end of turn. Learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)