Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Omniscient), First Person (Peripheral), and Second Person
It's clear from the first page of The Silver Chair that we have a narrator with free access to everything that is knowable about this fictional world. He or she (though we can probably assume he since this is Lewis' world—for more on this, read up on Jill over in the "Characters" section) sees Jill crying behind the gym and comments in the first-person about his intentions for the story. We know we're dealing with first person because the narrator busts out the I.
As we also immediately get a run-down of Experiment House, including all of the things that the Head of School thinks about the hardcore bullies—there's nowhere this narrator can't go, it seems, including into anyone's head they choose—and then we get some second person as we, the readers, are directly addressed in regards to how the bully system works and how we might thrive if we knew the right things to say. Lewis does this kind of thing throughout the entire book, so stay sharp while you read. And all the rest of the time, we hang out in third person, being told the story by a narrator who doesn't insert themselves into the text.
Sound like a hot mess? We assure you it actually works quite well—all told, the transitions are smooth and, if anything, the shake-up of narrative styles just keeps things interesting.