Middle English scole, from Old English scol, “institution for instruction,” from Latin schola “meeting place for teachers and students, place of instruction;” also “learned conversation, debate; lecture; disciples of a teacher, body of followers, sect,” also in the older Greek sense of “intermission of work, leisure for learning.”

This is from Greek skholē “spare time, leisure, rest, ease; idleness; that in which leisure is employed; learned discussion;” also “a place for lectures, school;” originally “a holding back, a keeping clear,” from skhein “to get” (from PIE root *segh- “to hold”) + -olē by analogy with bolē “a throw,” stolē “outfit,” etc.

late 14c., scole, from Middle Dutch schole (Dutch school) “group of fish or other animals” (porpoises, whales), which is cognate with Old English scolu “band, troop, crowd of fish,” both from West Germanic *skulo- (source also of Old Saxon scola “troop, multitude,” West Frisian skoal), perhaps with a literal sense of “division,” and from PIE root *skel- (1) “to cut.” Compare shoal (n.2)), the assibilated form of the same word. For possible sense development, compare section (n.) from Latin secare “to cut.”