The first Sonata that Mozart wrote as an adolescent, he was 22 at that time, is the Sonata in C major KV.296. It was written for Therese Pierron-Serrarius, who was his 15 year old student at the time that Mozart wrote it for her. He in their home during that period. It was during his trip to Mannheim that he wrote this work, like the other works ranging KV.301-306
This piece has the typical three-movement style that was so common for sonatas during his time. Mozart still keeps very traditionally in that the violin can really be seen as an accompaniment to the piano-part. The piano has a very solistic role in this piece, although the second movement already shows some special moments in the violin part.
We would suggest to the performer to compare both instruments regarding articulation. Mozart wrote in the first and third movement some very typical articulations in the violin part that could be slightly matched by the piano and give a nice effect to the playfulness of the piece.
The first movement can be seen as a very typical Mozart sonata for piano solo. This piece contains most of the typical 'Mozartian' aspects and is a great work to study the style of Mozart. As said before, the piano part is written like a solo-sonata and the violin has a very accompanying role, though near the end of the exposition there is a very nice canonic part. The development is not very extended and after a very powerful continuation, after the second theme brings us back to the recapitulation.
The second movement is an Andante that has extremely beautiful moments. The main line is for the piano but the violin does have more importance than in the first movement. Rhythmically the instruments are often together in the melody. In the middle part, the violin has the main line and the piano accompanies throughout. Before the return of the first theme, there is a small possible Cadenza for the violin, something that was not uncommon for Mozart to write in these sonatas, and the first theme gets played (for the first time) by the violin. Towards the small coda, Mozart wrote a lot of rests which gives a very special atmosphere, especially with the colors created by the instruments playing together.
The third movement is a Rondo in Alla-Breva form. It is a fast piece with the main line in the piano, though the violin has, again, more to say that in the first movement of this sonata. Mostly the violin repeats the melodies which were introduced by the piano part. Mozart wrote many characters, especially in the different part from the main Rondo theme and one should take care with especially the difference between the quarter and half note bass-line in the piano.