Wait a second... a preschool teacher is reading her preschool students "To Kill a Mockingbird?"
You think to yourself. This teacher is crazy. You could barely understand the words in that book. How would those three-year-olds be able to understand that book?
When the book was over (and it took forever to finish) the kids were asked questions. All those three-year-olds could answer perfectly with complicated words. They understood every part of the book!
When it is your turn, you have no idea. "Isn't that a high school book?" you ask the teacher.
"It used to be, Timmy," the teacher answers. "But we've discovered that starting at the age of three, any one can understand a book like that."
"But the books makes no sense to me!" you exclaim.
"Then obviously you aren't ready for this class. You will have to go back to the two-year-old class."