No. 25, also known as "Kakko". It has three movements, and like No. 24, it is a beautiful little piece that brings to mind a somewhat relaxing countryside scene. My teacher commented that I should pay attention to the notation "alla tedesca" at the beginning of the piece. I wasn't sure, so I looked it up and found that it means "German style. It seems to be a dance that was popular at the time. I typed it in to see if it was something like this.
Title: Piano Sonata No.25 in G mmajor, Op.79
Sound Source: Vienna Synchron Concert D-274
Audio file format: mp3