My four-year-old son recently showed a sudden interest in super heroes (Batman, Superman, et al.), but I could not find anything that I considered appropriate for him (i.e., not too scary and not too adult). This book fits the bill! It's a clever and engaging story about a boy and his friends at Superhero School who use their super powers--and the math lessons they've learned at school--to save their teachers from the evil ice zombies. (Don't worry! The zombies are not very scary.) He loves me to read it to him over and over, and I keep hearing him repeat his favorite lines from the book (e.g., "Suddently, it hit him like a giant mutant octopus!"). I think it will also be a book he will enjoy reading himself once he gets to that point. (He can already read some of it.) I would recommend this to anyone who is looking for a book for children ages 3 to 9 who are interested in super heroes.