In Ray Bradbury's "The Veldt," the children in the story—Peter and Wendy—lure their parents into the nursery where they are eaten by lions conjured from the children's minds. In the story, the nursery wasn't supposed to be more than a room that transports the children to whatever their imaginations will take them, simulating these worlds through "crystal walls," temperature controls and "odorphonics and sonics." However, as the story progresses, it becomes clear that the room has morphed into something "too real."
Wendy and Peter are upset because their parents have threatened to turn off the computer-controlled house and, by extension, the nursery. They've locked the nursery before and "the tantrum [Peter] threw! And Wendy too. They live for the nursery." George, the children's father, is very concerned about the "death thoughts" that seemed to emanate from the children's minds and show up in the nursery. Unfortunately for George and his wife Lydia, the children's death thoughts centered on them. There is foreshadowing present throughout, particularly the screams that "sound familiar." It turns out that these screams belong to George and Lydia.
Like he does with much of his science fiction, Bradbury uses "The Veldt" to explore what happens when humans give too much control away to non-human devices. In this story, the house and the nursery have replaced the parents and, as a result, when George and Lydia attempt to take away the house and the nursery, the children act in a protective, albeit violent, way.