[Grammar] Practicing a piano, or practicing on a piano

[themidd]

Pretty much the title, which one is right? Got into an argument today with my teacher saying the preposition NEEDS to be there.

 

[bhaisahab]

It is not possible to "practise a piano". You can "practise (the) piano" or you can "practise on a piano".

 

[Peedeebee]

I'm a pianist. (yes, really)
I can practise the piano as I would practise Tennis. (no preposition needed)

The piano is the skill I am practising. Just as I could study the piano if I were a full time music student.

I would usually say I practise on the piano if I am trying out a new composition or arrangement. "I am practising my new tune on the piano." ( To distinguish from practising it on the guitar.)

(Equally I would say I am playing the piano- not I am playing on the piano.)