My question is how badly would you say her playing is affected by the raised shoulders and close elbows?Is it a definite problem, or is she able to get a relatively good musical result despite the unorthodox position?That is very advanced repertoire for a person of that age.... and if they are really playing it nicely at 13, they should be pretty good.
...fix the posture!
Why assign an even more difficult work
I'd go with something with lots of long held chords; nothing overly virtuosic.
I've noticed that when the student plays she tends to keep her elbows close to her body and also sit quite close to the keyboard, and to compenesate she often has to play with raised wrists and shoulders.
Tell her that if she sits back a bit, she'll find it easier to play. If she does, the problem will be solved. If she doesn't, it's not a problem in the first place.
Allegro barbaro, by Charles Valentin Alkan. It's not too bad. i learnt that when i was around 13. My technique drastically improved after i learnt it. It's good for building endurance and loosening up... by hammering out some octaves.
holy fuk u were pro when you were 13 then
It was partially to challenge myself, since my teacher would never prescribed anything like that to me.