Late last month, ninth grader Marvin Chen was invited to guest conduct for the Terrible Adult Chamber Orchestra (TACO), a Bay Area community orchestra that welcomes musicians of all skill levels. Chen led the ensemble through a performance of Rossini’s “William Tell Overture” during their season-opening concert at the Los Altos Community Center. Chen, who began playing the piano at just five years old, also composes his own music and served as guest conductor for the middle school orchestra.