An easier lure for streams, that I started using when I was around your son's age was the Rapala floating minnow. I still use it some to this day. They can be fished with a straight retrieve, or retrieve pause, retrieve pause. The lure floats, so if he isn't able to keep a constant retrieve going, it won't snag the bottom. I would suggest the F05 or F07 size. They are lighter lures, especially the F05, so if he isn't proficient at casting yet, he may have a little trouble at first.

As other's have mentioned, inline spinners are great too (Mepp's or Rooster Tail), but may be a little easier to get snagged on the bottom.