Exact development uncertain, but apparently from a verb *leer, from leer#Etymology_2.
From Middle English ler, leor, from Old English hlēor, from Proto-Germanic *hleuzą, from Proto-Indo-European *ḱlews-, from Proto-Indo-European *ḱlewe-, *ḱlew-. Cognate with Scots lire, lere, Dutch lier ("cheek"), Swedish lyra ("pout"), Norwegian lia ("hillside"), Icelandic hlýr ("the face, cheek, countenance"). Related to Old English hlyst ("sense of hearing, listening") and hlysnan. More at list, listen.
From Middle English lere, from Old English ġelǣr, *lǣre, from Proto-Germanic *lēziz, *lēzijaz, from Proto-Indo-European *les-. Cognate with Dutch laar, German leer. Related to Old English lesan. More at lease.
From Middle English leren, from Old English lǣran ("to teach, instruct, guide, enjoin, advise, persuade, urge, preach, hand down"), from Proto-Germanic *laizijaną ("to teach"), from Proto-Indo-European *leis- ("track, footprint, furrow, trace"). Cognate with Dutch leren ("to teach"), German lehren ("to teach"), Swedish lära ("to teach"). Related to {{cog|ang|lār||lore, learning, science, art of teaching, preaching, doctrine, study, precept, exhortation, advice, instigation, history, story, cunning