Three things, Chicago:
TEACHER TENSION. At one of Chicago's largest -- and, lately, most troubled -- charter-school networks, teachers have voted to unionize.
SPRING TO SPURT. Buckingham Fountain returns to life at 11 a.m. Thursday.
NEWS BIZ NEWS.
-- Twitter is hiring "head of news and journalism."
-- PayPal cofounder: Twitter's outlook stronger than New York Times'.
-- Twitter app for iPhones, iPads updated.
COMING FRIDAY. A new news quiz. You know, like these.