Demonstrators gathered at City Hall yesterday to support the passage of the Student Safety Act, which would force the NYPD's School Safety Division to release detailed data on the race, sex, age, disability, and socioeconomic status of every city student who has faced suspensions, expulsions, and arrests at school. To put it in context, the New York Civil Liberties Union says the city's public schools have twice as many police officers (5,200) as guidance counselors. The figurehead for the burgeoning student-rights movement is Kew Gardens resident Alexa Gonzalez. In February, Gonzalez was escorted from her social-studies class for doodling on her desk with an erasable marker. At the dean's office, she had to empty her backpack, take off her shoes and sweater, and then have her pockets searched. After that, four NYPD officers were called, and walked her out in handcuffs with her classmates watching.