Early career....

Mark Goddard broke into films by appearing in non-theatrical "educational" films. In one of his first jobs he played a science teacher that turns a teen boy onto Jesus with some truly cringe-worth dialog as he helps the kid build a radio. He eventually became a teacher for real when good roles were not forthcoming. You can read about him in "They Fought in the Creature Features", an anthology of essays about sci-fi and horror actors.