Piano hand technique and posture Options

[Youngpianoteacher]

I am fairly new to teaching and I am wondering what other perople's experience is of hand technique in piano playing. By the way, this isn't a question limited to teachers, so please anyone with their thoughts feel free to reply...

I remember when I learnt I was simply told to keep my hand curved and to sometimes imagine a small ball in the palm of my hand. Other than this I have never really come across anything definitive, as most players tend to tell me as long as the sound isn't affected, it doesn't really matter.

Also there has been, as I understand, an evolution of thought between the 'finger-action' school of teaching, which devolves movement from the wrist and forearm and concentrates on the fingers to do nearly all the movement and the opposite which includes more movement across the whole arm. Is one way better? Does anyone know of any good material that discusses/tackles this issue?

Your thought and comments are greatly appreciated. Thanks everyone.

[Roseau]

Is it true that different countries teach different hand positions?
My oboe teacher (who is also a pianist) said something in my lesson the other day about the French school and the Russian school teaching completely different positions with the Russians favouring an almost flat hand and the French an almost exaggeratedly curved hand. I didn't want to waste my oboe lesson time talking about piano technique but have been wondering ever since whether what he said is true.