softball size

Question
What size softball does the 8 & under girls fastpitch use?

Answer
ASA doesn't have a 8U division.  I am not sure that any sanctioning organization does.  For ASA the 10U ball is 11".  ASA does have rules for a 10" ball but doesn't have an age group that uses it.

In my local rec league's T-Ball (6-8) division, they use low compression 11" balls.  The kids seem to handle that just fine.

I know it really isn't an answer, but I hope that it helps.