Walter O. Duncan IV, a middle school English teacher in Norwell, Mass., finds grading his 85 students’ quizzes a tedious slog, but the short, frequent reviews tell him what lessons stick and what he needs to reteach. Last year he began dreaming up a way to speed the process with his iPhone. The result is Quick Key, an app that scans the oval bubbles on students’ quiz sheets, tallies the data, and sends the scores into[:]