We're flies on the walls of the nursery, folks, because "The Veldt" is told from a third person point of view:
"Go to bed," [George] said to the children. (116)
That's a simple sentence that tells us what we see happening. Brace yourselves: George tells his kids to go to bed. Why does George tell his kids to go to bed? Well, we don't know, because this sentence doesn't tell us anything about his motivation, his thoughts, or even his facial expression. Here, this third-person narrator only tells us what we could see if we were flies on the wall of the Happylife Home.
But then, every once in a while, we also get some little (and not-so-little) glimpses into George's head. For instance, when George is eating dinner with Lydia and without the kids (who are at the carnival), we get to see all his thoughts about the veldt:
As for the nursery, thought George Hadley, it won't hurt for the children to be locked out of it awhile. (66)
The narrator has jumped right inside George's head and is giving us the skinny on what's going down up there. And the narrator is cuing us in on the fact that that's happening. But there are also times when the narrator will give us a glimpse into George's thoughts without telling us "George thought," like this line, from the next paragraph:
Death thoughts. They were awfully young, Wendy and Peter, for death thoughts. Or, no, you were never too young, really. (67)
How do we know that these are still George's thoughts? Because our oh-so-proper narrator would never do something so ungrammatical as speak in incomplete sentences ("Death thoughts"); and the narrator doesn't change his opinion—he's much too steady for that. George, on the other hand, is a little more fickle. Notice how George changes his mind while he's thinking: the kids are too young… well, maybe not.
We also know that these are George's thoughts because they continue the same line of thinking from the previous paragraph. So paragraph 66 told us, in a big neon sign, "These are George's thoughts," and then paragraph 67 continues the same thoughts in the same language. We're in his head. And we're trapped! (Okay, not really.)
Sometimes George's perspective comes through in just one or two words. For instance, George has looked in on "Africa" during dinner, but when he confronts his kids about it, Wendy goes and changes the nursery to some other setting. So when George and Lydia go back to look at the nursery, they find a beautiful jungle instead of the deadly veldt. And we get this line:
George Hadley looked in at the changed scene. (116)
When George looks in, he sees the beautiful jungle, but that's not what we hear first. What we hear first is that George looked at "the changed scene." Bradbury could've written that "George Hadley looked in at the scene," but by adding that single word "changed," he reminds us what George knows—that Wendy has changed the nursery. That one word tells us some mischief is afoot. And by mischief we mean deadly deeds.
Hey, you know what? Maybe this one word "changed" also gives us a clue about why he tells the kids to get to bed. Remember, in that simple line, we only heard about the external. We heard what George said but not why he said it. But in this line, we get a clue: George tells his kids to get to bed because he knows that this room was changed. In other words, George knows his kids are lying liars telling lies about Africa. It's bedtime for the little baddies.
But given all this narrative technique, here's the real question: if so much of this story is filtered through George, why not just write a first person story? Because:
(1) we know that George isn't crazy, because the narrator also told us that the room was Africa. Phew.
(2) we also get to see what George thinks about this problem, which is kind of the point in a story about parenting.
But how do you think this story would be different if we heard about it from Lydia's or the kids' point of view? Would Lydia think her husband is being stupid for not seeing what she sees so easily? Would Peter see his parents as villainous tyrants? Would Wendy see David McClean as this weird invader instead of as a walk-on expert?