When my daughter was 9, I bought her a St. Croix "Triumph" rod.
It's a 7 1/2 foot 4 weight.
St. Croix Fishing Rods - Spinning, Casting, Saltwater, Fly
One of the things I like about it (beside that it was cheap) is that it has a medium action, and it's easy to feel the fly line flexing the rod. I started her out on one of my faster action graphite rods, and it was harder for her to learn the casting stroke and rhythm. She picked it up much more quickly once I had her cast the slower action St. Croix.
The shorter length is an advantage as well. Makes lots of things easier for a child, like stringing the rod, changing flies, etc.
So, my advice would be to get a medium action rod, in a shorter length. A 4 or 5 weight would probably be a good choice. 4 weight would be better for panfish, 5 weight better for bass.