Fortress (1985)

One might view this as the polar opposite of "Lord of the Flies", although both give very credible depictions of kids in dire circumstances.
The difference here is that there is a teacher with the kids to guide them.
Also, there is no plane crash. Instead, the kids are kidnapped from a very remote school in a very remote place in Australia.
There are a lot of very interesting aspects to this film. First of all, the protagonists of a beautiful female teacher and her students in a place so remote that all the grades and ages are combined in one tiny class, so we get older kids and younger kids.
Then there are the antagonists, the four kidnappers. They wear masks. One, Father Christmas, is super dangerous. Another, the mouse, is also quite dangerous. The other two have their own problems. "Kitty cat" appears to be someone who might today be on a "sexual predator" list, and the duck is the most reluctant of the group.
Instead of "spoiling" the stroy, I'll leave it at this to let you go through the adventure, and there are lot of adventures that the protagonists go through.
The reason I say it is the polar opposite of "Flies" is that instead of behaving horrible to each other, they work together to try to survive against the maniac who torments them.