( Macworld rated 4 out of 5 mice ), a $2 universal app from , takes a very different approach. The app launches with a massive, vertically scrolling alphabetical grid. Kids can tap on any of the squares--some of which preview their contents, but most of which don't--to see objects that start with the corresponding letter.

Once you're on that object, you have plenty of options. For example, we tapped on B, and were presented with a colorful, full screen image of bumper cars. Tiny characters--whom ABC Go dubs Little Explorers--hold up signs that spell out the word(s). Swiping reveals another picture of bumper cars; swiping again reveals a third. Many photos (including each of the three bumper car images) are also linked to videos. Tapping the video button plays an embedded YouTube video--pre-screened for appropriateness by Peapod Labs--on the topic. Tapping the exclamation point button displays a factoid ("Bumper cars draw power from the floor and/or ceiling of the track, and they can be turned on and off remotely by an operator"), which my own kids quickly learned never to bother with. After swiping past the last of the bumper cars, we were guided directly into the app's showcase for its next entry: bus.

But you needn't navigate alphabetically. Tapping any of the letters in the written word--say, the "s" in "bus"--instantly transports you to a new object. In this case, that would be "steamroller."

I vacillate on whether the app's high quantity of more unusual words is a feature or a detraction. There are many words your kids likely won't hear much elsewhere ("gondola," "hovercraft," "maglev," "omnibus," "quad bike", "news van," "xtrapolis"), which might broaden their horizons, or might leave them a bit confused. (Peapod offers a similar app called that showcases animals instead of means of transportation; the words in that app are a bit more accessible overall.)

Regardless, my kids love ABC Go. I'd love an option to turn off the videos; we limit our kids' video-watching time, and my four-year-old sometimes likes to use ABC Go for noun-based channel surfing. And the app's endless musical backing track can start to grate after its dozenth loop. These quibbles aren't major, though. The pictures are great and engaging, the words are pronounced clearly with focus on their initial sounds, and the app is a snap to navigate.