Pigeon Presents...Mo on the Go! (Hyperion, July 2013), Mo Willems's second app, offers five activities populated by animated characters from his books. As in Don't Let the Pigeon Run This App!, there's lots of interactive Willems wackiness.

"Leonardo's Monster Maker" invites users to mix and match monstrous features to create a customized monster. Once completed, the animated monster attempts to scare Leonardo and his friend Sam; their reactions range from "Meh" to "That scared the tuna salad out of me!"

In "Elephant and Piggie's Dance-o-Rama," users choose three dance moves for each of the friends to perform. Elephant and Piggie mainly dance solo; however, certain combinations of selections initiate special pas de deux. The upbeat music changes each time through. Occasionally Mo himself shows off his moves.



In "Pigeon's Dream Drive," users trace a route for a bus — driven by the Pigeon, natch — to follow, picking up groups of ducklings at bus stops along the way. Animated vignettes and funny interjections from the Pigeon punctuate the drive. Obstacles (such as a roving mad cow) and additional ducklings appear as the levels progress.

Mo introduces "Mo's Squillems" with a video tutorial. What's a squillem, you ask? "Good question. It's a drawing that two people — like you and me — make together." Users add their own drawing to a squiggle provided by the app. Two-player mode allows users to create a squillem together.

Completing the activities earns stickers for "Knuffle Bunny's Sticker Pictures," in which users embellish the sepia-toned backgrounds from Knuffle Bunny (or photos of their own) with stickers of various Willems characters.

Audio explanations of the activities and no reading required make this app a great choice for pre-readers. The activities are engaging enough and substantial enough for many repeat uses. And while — perhaps with the exception of "Dance-o-Rama" — these types of activities may be found in plenty of other kids' apps, other apps lack Willems's signature wit and beloved characters. Note: The app crashed frequently during testing.

Available for iPhone, iPad, iPod touch (requires iOS 4.3 or later), and Nook; $3.99. Recommended for preschool and primary users.