I was hacking along quite nicely in System 7 at that age. But to get her started At Ease sounds like a good idea, then limited Finder and lastly full Finder as her reading improves. Kids learn these things very fast.
Edit: I remember OS9 having At Ease-like functionality built in, look in the control panels.
II, II, SE, SE/30, IIcx, Portable, IIsi, IIsi, IIsi, LC, Classic, Classic II, Quadra 700, PB 100, PB 170, LC II, LC II, LC 475, PM 6100, Perf 6200, PM 7600, MP 2000, Perf 6400, PB G3, PM G5, MB.