PreS-Gr 1 This first book in a new series introduces Blippo and Beep, a dynamic duo of friendly robots. Beep tries to tell knock-knock jokes to Blippo, who is unfamiliar with the format. Blippo answers, "Come in!" to Beep's first attempt at a joke. When Beep is finally successful in delivering the joke, Blippo doesn't fully understand the humor. But he goes on to learn how to tell his own kind of joke to make his friend laugh. The story is told using short speech bubbles for the dialogue between Blippo and Beep. Ellis adds clever details in the bright illustrations, such as a question mark on Blippo's stomach when he is confused, a smiley face when he is happy, and an exclamation point when he is excited. The entire book is illustrated using only five colors: white, black, blue, purple, and yellow. Weeks has created two likable robots, one more serious than the other, but both eager to make the other happy. VERDICT Fans of Mo Willems's "Elephant & Piggie" series will enjoy this book that follows a similar pattern with different characters.Heidi Dechief