I Spy Challenger!

I Spy is an American children's book series, first published in the 1990s, with text written by Jean Marzollo, and photographs by Walter Wick, from Scholastic Press. Each page contains a photo with objects in it, and the riddles (written in dactylic tetrameter rhyme) accompanying the photo state which objects have to be found. I Spy merchandise has been sold in at least 31 countries worldwide. Although the first I Spy book contains unrelated pages of still life pictures, subsequent books are more thematic.