In Bobo Explores Light by Game Collage (September 2011; updated June 2012), Bobo, a cute robot with an appropriately light bulb–like head, is our guide for a quick trip through the solar system toward the sun—and from there, onto a discussion of light in its many forms.

Bobo takes users on a roughly chronological review of humanity's history with light, from dependence on environmental sources (sunlight,  moonlight, lightning) and the discovery of fire to the invention of the light bulb and the laser. Once caught up to contemporary technology, this app covers various principles related to light, including vision, color, reflection, refraction, chemical-based luminescence, bioluminescence, photosynthesis, and the aurora borealis.

The app moves naturally from topic to topic, introducing each on its own screen with a short, conversational paragraph and a few humorous interactive moments. Pull-down tabs offer pleasantly narrated video clips, lists of quick facts, and in-depth explanation of concepts. A table of contents with thumbnails of each screen makes for easy navigation between subjects.

Though at times the language is not entirely scientific (e.g., "plants have little magic things called chlorophylls, which grab photons and store their energy"), overall the information is solid and presented clearly. Tapping Bobo's "holo-projector" provides relevant diagrams and calculations. Several simple activities allow users to test the principles themselves by arranging mirrors to reflect laser beams or mixing colors. Cartoon-like illustrations, interactive animations, music (both instrumental and Bobo's humming), sound effects, and a postcard function add to the fun.

This accessible app will engage young scientists for hours, then inspire them to find out more. Great for summer traveling or paired with a trip to the science museum.

Available for the iPad (iOS 4.3 or later); $4.99. Recommended for primary and intermediate users.