Four Los Altos student pianists will be performing at the Gala 100th Anniversary celebration of the Music Teachers' Association Of California. The event will be held at the Sheraton Palace Hotel, San Francisco, July 4-8. Students are chose on the basis of superior test scores in their annual four-part exams at Stanford. Those participating in the festival and dance theme recitals are: Kristine Hanson, Christopher Mar, Sarah Sasaki and Ken Yuan. Their teacher is Jan Edwards of Los Altos.