Wolfgang Amadeus Mozart's Piano Sonata No. 7 in C, K. 309 (also 284b) is a work in three movements, written in 1777. The work was composed in a few days, during a journey to Mannheim and Paris. The andante movement is a "portrait" of Rose Cannabich (his pupil), the 13-year-old daughter of the Mannheim Kapellmeister Christian Cannabich. Upon reviewing a copy of the manuscript, Mozart's father Leopold wrote that it was "a strange composition. It has something in it of the 'rather artificial' Mannheim style, but so very little that your own good style is not spoilt". A typical performance takes about 16 minutes.
