I would like to second the nomination of the Firebird XL. You guys have to remember that these are really little kids we're talking about here. They'll be thrilled just to make the airplane go round and round. When they get comfortable with that one, then you can move them up to the glow trainer.

The Firebird XL is slow, and has an ideal flight interface for young pilots. You can't go down; it's climb or glide, based on throttle. The throttle and turning controls are in their proper Mode 2 locations, so moving to a regular plane will be a breeze.