Built in 1930 in the Mission-revival style, Howard Spencer Hazen's Physical Science Building was originally the training school for the college. The building formed the east side of the Quad and had 30,544 square feet of space, which included an auditorium for the showing of films and slide materials and a library for the children who attended the Campus Lab School.

The Physical Science Building contained wood beam ceilings in the outside corridors, wrought iron trim, and many arched doorways. A small patio, called the "Banana Quad," in the building's courtyard was cared for by the grammar school children who attended the Training School. A functioning elementary school, it was a facility for student teachers to train and be evaluated while teaching in actual elementary school conditions.

The Campus Lab School relocated in 1952, and the Physical Science Building underwent modernization, including covering the original stage area with a false wall. In the 1960s, the building provided classroom and office space for the physical science, math and astronomy departments.

The Physical Science Building is now a multipurpose facility. It houses numerous science laboratories, research groups, conference rooms and classrooms, and the Astronomy Help Room. A beautiful Mediterranean garden with a fountain now borders the west side of the Physical Science Building, featuring benches and tables for outdoor dining and studying. The Banana Quad still flourishes in the east courtyard.