question about trill fingering in mozart's sonata k331

[enissimo]

Hello all,
I'm learning Mozart's sonata k331 now and have questions:
In the opening bar of 2nd variation, should i play the trill as EDEDCDE (3232123), or DEDCDE(232123)? which way is more preferable? my teacher suggests both but from the recordings i listen to seems the later version is used more...please help : ((((
Thanks !!!

[kitty on the keys]

What is the note preceeding the trill? If it is the same as the upper note of the trill use the main note not the note above. But your teacher is correct--experiment--see what works musically--as long as you kow the rules first---then make an educated decision.

Kitty on the keys

[faulty_damper]

Yes, always listen to how it should sound in context.  Sometimes these 'rules' are incorrect. 'Rules' are really just theories of how things are. 

[scottical]

Start the trill on the auxilary, or upper note.  You want the dissonance of the trill to be prominent in the music you are playing, otherwise it sounds like a mere vibrato of tone.  This is the traditional method of executing ornaments in the Baroque and Classical eras. 

On the contrary, Muzio Clementi wrote a rule for ornamentation regarding this technique.  If the note preceding the trill is the same as the auxilary note, it can be left to the discretion of the performer as to what note it begins on.  This is avoid a break in the legato.