For those curious about the above question, here's the short answer: No. Elizabeth never becomes a good teacher. In some ways, she gets worse. But she does become a fractionally better person.
We're not talking a lot of growth, mind you. But she does dole out one grudging compliment to a student and dish a bit of backhanded advice. She helps a kid get over a hopeless crush and even tries to boost his social standing (albeit in a horrific way). By the time the credits roll, she's begun to see that her materialistic search for sugar is a little selfish. (That said, most of her advice is fairly toxic.)
Elsewhere, lots of folks mean well and genuinely try to care for kids, be they teachers or parents (even as the film itself relentlessly mocks much of their altruism).
Past lives get a wink and a nod. Santa and Jesus get a half-hearted apology pushed their way after a disparaging comment is made about Christmas.
Elizabeth goes to a plastic surgeon, and one of the surgeon's former patients displays his "work" to her by cupping her exposed breasts in her hands and moving them around. Then Elizabeth checks out realistic Photoshopped mockups of how she'd look after the operation, which picture her head grafted onto various virtual nude torsos. She circles (clothed) celebrity breasts in magazines, apparently to use as illustrations of what she'd like to look like in the future.
Her upcoming operation is the talk of the school, often referenced in the crassest of terms.
In her quest to find the perfect rich husband, Elizabeth realizes that her most formidable weapon is her body—and she bludgeons the audience with most of it throughout the movie. She dresses in Daisy Duke shorts and a scanty, midriff-baring shirt while "supervising" a 7th-grade car wash fundraiser, spraying water over herself (in slow motion) and writhing on cars to attract customers. A fellow female teacher and many, many others ogle Elizabeth. A gawking police officer crashes into a minivan, and a student develops an erection that's visible through his pants. Even apart from the car wash, she's almost always dressed provocatively.
Elizabeth has "sex" with another teacher in a hotel room during a school field trip. Sex is in quotes because both remain fully clothed. But that doesn't help much when it comes to explicit content: He thrusts against her from the rear and a wet spot on his jeans signals his climax. Elizabeth also seduces a standardized test official: Plying him with drink, she encourages the man to take her to his office so they can have sex on his desk. He passes out before anything happens (because Elizabeth drugged his wine), but she later blackmails the fellow with pictures of him naked that she snapped of him in the aftermath. (His midsection isn't pictured onscreen.)
Elizabeth encourages her fiancé to get an erection so she can perform oral sex on him, not realizing the man's mother is in earshot. The two break up shortly thereafter, and she spreads rumors about him, accusing him of homosexuality, bestiality and incest. She also tells a teacher she'd like to land an NBA player as a husband, but she's frustrated because they always use condoms and then take the condoms with them (so she can't impregnate herself and entrap them).
A principal confiscates porn magazines from a student. A teacher dirty dances with a cowboy at a bar. Elizabeth gives a student her bra, and then spreads the rumor that she'd caught him in sexual relations with an 8th-grade girl. The boy, for his part, proudly whips out the bra and tells his friends that the 8th-grader was wearing it. A teacher makes an obscene, sexual gesture.
Elizabeth and Russell hit each other's shoulders and chests. Elizabeth tries to teach students about To Kill a Mockingbird by playing dodgeball: If she deems a student's answer dumb, she hurls a ball at him. If it's a good answer, she lets him throw a ball at her. Another teacher gives pointers on how best to throw a ball, and the projectile promptly smacks Elizabeth in the head.
Drug and Alcohol Content
Elizabeth drinks quantities of alcohol and frequently smokes marijuana, sometimes encouraging others to do the same. We see her toke on bongs, pipes and joints (as do others), and she keeps a collection of pot, liquor and unnamed pills in a secret compartment in her school desk. Many people drink wine, beer, champagne and mixed drinks. Elizabeth encourages one of her patsies to get drunk, then drugs his drink to frame him. She continually talks about her desire to be drunk or high.
Other Negative Elements
Elizabeth lies a lot, cheats a lot, steals a lot and, in the end, is allowed to escape all of the consequences for her inexcusable behavior. She indirectly frames fellow teacher (and primary rival) Amy Squirrel for drug use, forcing the (rather annoying but undeniably dedicated) educator to resign. Elizabeth also rubs an apple with poison sumac (or something similar) and leaves it for Amy to eat. She does, and a rash breaks out all over her face—forcing her to bow out of an overnight 7th-grade field trip.
Amy barges into the men's restroom and tries to hold an impromptu meeting with the principal as he's sitting in one of the stalls. (She sits on a urinal at one point.) After she leaves, the man using the stall next to the principal unleashes a loud bowel movement.
Elizabeth uses several racial epithets. She encourages one of her students to become a masseuse rather than aspiring to be the president. She tells another that unless he stops wearing a ratty sweatshirt, he won't have sex until he's 29. When he says the sweatshirt was the only thing his father left him when he abandoned the family, Elizabeth quips, "There's a reason he didn't pack it."
For the entire first semester, Elizabeth's English class consists of unrelated movies, including the R-rated Scream.
There's not much left to be said about Bad Teacher. It's a bad movie: bad artistically, bad ethically, bad to its cinematic core. It's about a bad person who does bad things and winds up being the film's big, bad antihero.
And the film's been hit with bad reviews from secular reviewers, too. One example: "Misanthropic to the extreme, Bad Teacher fails across the board," writes USA Today's Claudia Puig.
This movie teaches all the wrong lessons in the worst ways. If you find yourself in this Bad Teacher's class, request a transfer.