This is a preachy episode that tries to extol the uber-importance of education by painting one-dimensional, knee-jerk people as the backdrop for its sermon. The audience is supposed to believe that an entire region is not only uneducated, but they have no manners, no hygiene, and no kindness as well.
But what's even more annoying and even a little less believable than the townsfolk is Mary Ingalls and her mood swings. One cringes as she flies off the handle, first at her student Joshua, then at the guy who houses her, then watching her belt Joshua a little later as she hollers at him.
By the end of the episode, Mary's screaming really starts to work the nerves. You're kind of ready to give her a closeup of a mud puddle before shipping her back to Walnut Grove. Not only that, she's extremely self-righteous in her quest. Her tactics, which we're supposed to identify with as zealous, come across as that of a punk - mouthing off to those who are feeding and boarding her and paying her, essentially. Going low and slow, that is, proceeding in humbleness and kindness, even to the meanies, would probably help her cause a lot better.
Miss Peel isn't a religious fanatic; she is a witch (which Mary even admits to Pa). Peel exhibits this in her control tactics and also the charm she makes to keep away health issues. The manipulation she exerts over the town is supposedly out of her own ignorance, but it's the essence of witchcraft all the same. There's nothing really religious about her, except for spouting off scripture (which Satan himself does) so the convincing falls flat.
All in all, if you worship at the altar of education as the answer to all the world's problems, you'll eat up this episode - and Mary's frequent meltdowns.