Robert Donat plays an extraordinarily caring teacher, a schoolmaster who loves the classics and the students in his charge, in this 1939 movie that is itself, by now, one of the classics. But there’s another reason to watch these days: When Breaking Bad creator Vince Gilligan sold his series, it was by describing the dramatic arc of his leading character, who goes from science teacher to meth dealer and murderer, as “Mr. Chips becomes Scarface.” Tune in, then, to see Walter Whi