OK, in the world of beginner planes, there are a few good choices. If he's going to just run down to the park, you need to make sure you get something that flies slow and deliberate. Most of the starter planes are ARF, but require some assembly. I think 3 of the most popular ones are the GWS Slow Stick, the Multiplex Easy Star or something like a HobbyZone Firebird series. Of those, I'd be all up on the Slow Stick because it flies slowly enough for a beginner. It has rudder/throttle/elevator control. And it won't go so fast that it will be hard to track in a park. The Easy Star is nice, but has a bigger wingspan which might make it a bit trickier in a small park. The Firebird planes usually are inexpensive and fly pretty docile. Not a bad way to get started, but you guys will probably step up to something else before too long.