Riiid is one of a handful of companies that believe that A.I.’s algorithms are perfectly suited to track student performance and give individualized attention.
Mr. Musk said that he would resign as Twitter’s chief executive once he found a successor “foolish enough to take the job.” YouTube reaches deal for the rights to stream N.F.L.’s Sunday Ticket games. And Mark Zuckerberg appears in court in an antitrust hearing.