This book is about a young (5 years old) boy named Dibs who has some pretty severe emotional problems. He keeps to himself all the time and doesn't really talk much to anyone. Over the course of the book, Virginia Axline, who pretty much invented play therapy, is able to get through to Dibs. As it turns out, he is a brilliant boy. The story follows all the difficulties that lead to this triumphant end.
In the first paragraph of the story, Dibs is withdrawn, like he usually is. All the kids in his class are getting ready to go home, but he is not. His teachers are watching him "surreptitiously." This means that they are watching him in a way that he will not notice. The word "surreptitiously" has nothing to do with child development -- it just means doing something but trying to keep others from noticing that you are doing it.