Spatter & Spark (Polk Street Press, February 2013), a picture book app written by Deborah Underwood and illustrated by Luciana Navarro Powell, celebrates friendship and creativity.

Artist Spatter (a porcupine) wants to paint a portrait of baby crow Hubert but runs into a small problem: since the fledgling is too young to leave the nest, Spatter doesn't actually know what Hubert looks like. Undaunted, Spatter asks his inventor friend Spark (a fox) for help. After much trial and error, the friends build bouncy shoes (which Spark — with the help of the user — embellishes with glitter paint). They underestimate the strength of their invention, however, and wind up bouncing far above the crows' home. All ends happily, of course, with the pair's paws on solid ground and an appearance by baby Hubert.

Powell's digital illustrations capture the layered, textured look of mixed-media collages, and the warm palette has a friendly feel. A few animation, sound effect, and activity surprises on each screen enhance the slightly zany story; these are particularly fun when they set off Spark's Rube-Goldberg-machine-like inventions. (One of my favorites? A pint-sized hot-air balloon/watering can piloted by mouse Ava.) An upbeat ragtime soundtrack adds to the sense of cheerful chaos.



"Read to me" with text highlighting and "read to myself" options are provided. The navigation, with a pull-down menu of scene thumbnails, is intuitive and requires no reading.

While Spatter & Spark has a lot going for it, it also has a few technical glitches. The screens load slowly, and occasionally the text, text highlighting, narration, and animation elements do not work simultaneously as intended but lag a few seconds behind one another. I hope to see these hitches worked out in future updates.

The storybook app itself is free; four companion apps with activities featuring Spatter, Spark, and their creative endeavors are available as in-app purchases behind a parent lock ($1.99 each or $3.99 for all four). Behind the locked section, parents can also set up a free account to monitor their child's development as indicated by interaction with Polk Street Press apps — if you're into that sort of thing.

Available for iPhone, iPad, and iPod touch (requires iOS 5.1 or later and optimized for iPhone 5); free. The "pro" version, with story plus activities, is available for iPad 2 or later for $3.99. Recommended for primary users.

See our review of Polk Street Press's app Goodnight Safari (also illustrated by Powell) here.