This book is different from most "I-Spy" books in that rather than looking for hidden objects in a picture, you are looking for differences between two seemingly identical photos. Some of the challenges are more interesting than others - the hockey card/table game page is amazing, the referee page is not quite as visually stimulating (although, truthfully, a more suitable challenge for younger readers than the aforementioned hockey card page). The other unique thing about this book is the "Photo Facts" - they teach a bit about the game or history of the game. It's really cool. Keeps the kids busy for a while and great for all ages. I frequently give it as a gift to young hockey fans.
From the book: "I spy with my little eye, women and girls on the ice. The home team moves away, some colors stray, look up at the scoreboard twice"
Photo Fact: "...one of the earliest photos of a women's hockey game dates back to around 1890..." COOL!