So I talked to daughter this morning. About the list above by horselovinguy--she's not allowed to toss against the wall, no matter how gently, as this is called "breaking it all up" by the BO. In the stall only sifting allowed.
She tries to do the same as BO--in a circle, overlapping. Pretty similar to the list, I think.
Daughter says BO stalls always look whiter than her own, but when she tries to copy, the BO tells her she wastes too much bedding.
There's no doubt that the BO is very efficient and perfected her technique of sifting and what not, especially compared to a kid, no matter how conscientious and hard working.
My guess is that the BO is upset with *herself* for *NEEDING* to "waste" bedding in order to achieve her own high standards, but instead she criticizes my daughter.
If daughter wants to continue riding there, I probably shouldn't talk with the BO, but should just withdraw her from volunteering, claiming that she needs to focus on school work or chores at home, or something.