Children's Literature, Briefly ch.3

Chapter three touched on controlled vocabulary. Children are often taught to read through controlled vocabulary. They learn simple words first, then graduate to larger words. The text books often use word patterns that sound unnatural and are not fluid like everyday speech. The chapter suggests as teachers we should divert from controlled vocabulary to natural text. The book does not give an example of natural text. Do public schools let you choose reading text books? I thought that all grade level classes used the same text books, and followed the same reading curriculum.