Christian parents far less fanatical than Margaret White are known to homeschool their children for religious reasons. Why doesn't Margaret just homeschool Carrie (or send her to a Christian school) instead of letting her attend the public school where she'd be exposed to the sinful influences of her classmates and teachers? (One of Carrie's classmates even asks this question in the 2002 version.)
Think about it. Margaret is a widow who works full-time; she doesn't have enough time to devote to homeschooling Carrie. As for Christian school, it's stated in the book that she works at a laundry, which is hardly a job that pays enough to send a child to private school, and furthermore, knowing Margaret, any religious school would most likely fail to meet her strict definition of "true" Christianity. Better that Carrie go through public school with no religious instruction, allowing Margaret to fully shape Carrie's beliefs, than have her receive heretical religious instruction that Margaret would have a much harder time getting out of Carrie's head.
Furthermore, in the 2013 version it's mentioned that the state stepped in to force Margaret to stop homeschooling Carrie and send her to public school. It appears that Margaret was too fanatical to homeschool Carrie, as apparently, her... methods got the attention of social services.
Margaret gets labelled as Too Dumb to Live for mistreating Carrie when she knew her daughter had access to insanely powerful telekinesis. However, it can be interpreted that she was trying to make Carrie so afraid of her that she would forget that she even had powers — in a sense, trying to "squash it out of her", similar to the Dursleys and Harry Potter.
While this might not cross your mind initally, the primary, secondary and tertiary protagonists and antagonists appear to be the opposite of each other if you think about it.
Carrie and Chris (primary protagonist and antagonist) are obvious — they are the outcast and the Alpha Bitch, respectively. Furthermore, in the '13 version, Chris' arc during the finale mirrors Carrie's. Just as Carrie had been driven over the edge by Chris' prank, Chris herself gets her pig blood moment upon witnessing Carrie's reaction to said prank, and especially after Carrie kills her boyfriend Billy. Chris becomes so blinded by rage and/or fear that she presses on with her effort to kill Carrie even though it's clear to anyone with any sense that she's doomed.
As for Sue and Margaret (secondary), Sue has been described as the "fairy godmother" to Carrie's Cinderella, while Margaret clearly covers the Wicked Stepmother aspect. While Sue tries to make up for her initial bullying of Carrie, Margaret harbers little to no remorse and even tries to kill Carrie. Also In the 2013 version Sue and Carrie apparently make some sort of peace shortly after Carrie killed her mother.
Lastly, there's Tommy and Bill (tertiary). Tommy's a Lovable Jock and a nice boyfriend to Sue, while Billy is a Jerk with a Heart of Jerkdelinquent who is abusive to Chris. Also both Sue and Chris respectivly ask Tommy and Billy for a favors during the prom involving Carrie. Sue asked Tommy to take Carrie to prom and give her a wonderful night, while Chris asked Billy to help with the prank that ruined the night for Carrie and by extention the town. Also if you take Carrie and Chris's differences into account, Billy and Chris are an Official Couple, while Tommy, while the closest Carrie has to a romantic interest, but they are hardly a couple.
After the release of the 2013 version, there has been a lot of debates around whether or not Chloe Grace Moretz was the right actress to play the role; many had as an argument that she was too pretty for the role. However, keep in mind that the 2013 film is a modern rewrite of the original Carrie story. In fact, this becomes a plot point, as Chris records the event where the group of girls bully Carrie in the girls' showers. Later, that video is put on Youtube. There was video proof that Chris bullied Carrie. Plus, the video is played during the big prank, after the pig blood is dropped on Carrie. Cyberbullying IS an aspect of today's bullying. What else? Well, bullying has become a big topic in schools, and we've had many examples of otherwise pretty teenage girls getting bullied. It doesn't just hit girls who are below the standards of beauty, now it can make any girl suffer, regardless of their appearance. In a way, this modernized remake also modernized that aspect: Any girl could fall victim to bullying, and so Carrie could be played by a good-looking actress, exactly because those things aren't unheard of anymore.
Moreover, the 2013 version strongly implies that it was Carrie's social awkwardness, lack of knowledge of things everyone takes for granted (such as menstruation) and being branded a religious fundamentalist because of her mother that led to her bullying, rather than her appearance. These in turn were very much the result of being raised by Margaret. Also, some students are shown to treat her well, such as the male student in the library who showed her how to use the computer when she was researching on telekinesis.
The film does a pretty good job of illustrating that Chris is the only one who really has anything against Carrie personally. (Notice how the other students all clap for her and are genuinely happy when she is voted Prom Queen. Also, no one other than Chris objects to being given detention for hurting her with the locker room prank, not even Chris' own followers.) So why does everyone in the girls locker room participate in the locker room prank? Because Chris was doing it. This is the Alpha Bitch we're talking about, de facto head of the student body and social queen, capable of destroying your good name with a single word. They didn't want to hurt Carrie, but no one wanted to be the one who didn't go along with Chris. This kind of peer pressure is also how Real Life bullies gain followers too.
There's also the mob mentality as well. The rest of the girls were likely just caught up in the joke of it all. To them it was just a harmless bit of fun. At their age they couldn't possibly realise just how horrible it was until afterwards. Sue probably wasn't the only one who went My God, What Have I Done?.
Sue says as much in her in-universe autobiography. She stresses over and over that "we were kids" and they had no idea the extent of what they were doing.
This is more explicit in the book, especially at Sue's testimony before the White Commission. Given what happened, it's doubtful therapy would do her much good...
It's also confirmed in the sequel that she spent time in a psychiatric ward after what had happened.
If this book were to be taken into account, because of Carrie's actions, science at the setting of the story's timeline is taking telekinesis seriously. Therefore, there is a possibility that, since the events of Stephen King's books exist in a continuity (take a look at It, for example), then it might had been linked to the events in Firestarter as well.
But if so, then the government would have to have known about Psychic Powers long before the "Carrie White incident" in 1979, given that the Shop was operating back in the late '60s/early '70s... which means that the government was actively trying to cover up the existence of Psychic Powers for at least a decade. Before Carrie White's rampage finally made the existence of such abilities impossible to deny, just how many smaller incidents happened and got dismissed as "gas leak explosions" or whatnot?
Even if the prank hadn't happened, Carrie's situation wouldn't be good after the prom. There are only two possibilities for what could have happened afterwards.
First, Tommy breaks up with Sue and stays with Carrie. Sue's reaction is not likely to be pleasant; she may have been genuinely remorseful over the shower prank, but the fact that she took part in it in the first place shows that she's not exactly a golden child. If she sees Carrie as having "stolen" her boyfriend, then she could well turn into another Chris.
Second, Tommy breaks up with Carrie after the prom and goes back to Sue. Considering that Carrie was already skeptical about Tommy's intentions, this could quite possibly make her think he was leading her on and that this was all a prank. Carrie is left heartbroken and feeling like she'd been stabbed in the back, and her Roaring Rampage of Revenge is merely delayed.
There's also the third issue of what might have happened if Tommy went back to Sue, only for her to learn about Tommy's implied attraction to Carrie. This combines the worst of both worlds, with both Carrie and Sue pissed off.
A solution (as unlikely as it seems) to this: Carrie and Sue work shit out and they end up in a polyamorous relationship with Tommy.
Considering that Carrie's a devout Christian, I really don't think she'd cotton to that kind of arrangement.
Actually, she already knows (or otherwise implied) that Tommy went out with her because Sue asked him and to be kind to her. She could have simply thanked him for being nice to her and they could have been friends afterwards.
One thing that a lot of people ask is why nobody stepped in to seriously help Carrie and end her bullying. The answer: Values Dissonance. Stephen King (a former high school teacher) was writing from experience; adults just did not care about bullying back then, even when it got so out-of-hand, seeing it as just child's play.
Even then, that still happens a lot nowadays. Adults don't call on abusive parents and kids won't say anything about bullies.
At the end of the 2002 version, how was Sue able to resuscitate Carrie? The longest anybody has survived being submerged underwater was an hour; Carrie would've certainly died of suffocation and undergone total brain death (putting her far beyond hope of revival) after spending what is implied to be most of the night submerged in a bathtub.
In the book it's explained that Sue had a psychic link with Carrie the night of the rampage and that was how she was able to track her down. It's likely that's what happened here and Sue arrived at the house only a few minutes after Carrie drowned. I always assumed she had gotten there pretty soon afterwards.
How is the pig's blood still fresh enough to still be a runny liquid? It was up there early enough for Sue to see (and presumably smell) the bucket in the rafters while she's decorating the stage during school hours the day before, surely it would be a thick, probably partly-crusty clotted blob by then. And for that matter, why didn't Sue tell anyone it was there?
Maybe the pranksters added an anticoagulant substance to the blood beforehand?
It's mentioned in the book that they had chilled the blood beforehand, though this is never mentioned in the films. In the book, there are also two buckets of blood, and what falls on Carrie is clotty and streaky, but there's still enough liquid for it to cover her.
What difference would that make? It was up there for at least a full day. Even if it were chilled before it would have warmed up and thickened long before the prank.