From the event website:

"The Bay Area Mathematical Olympiad (BAMO) consists of two exams, each taken by over 200 students, with 5 proof-type math problems to be solved in 4 hours. One exam is for students in 8th grade and under, and the other for students in 12th grade and under. They are held on the last Tuesday of every February, at schools and several open sites around the Bay Area."