What is your opinion and perspective on effective and ineffective school security measures

What is your opinion and perspective on effective and ineffective school security measures

Over the past few years, there has been a lot of controversy about the best approach to school security (let’s assume the Middle School through High School setting). What is your opinion and perspective on effective and ineffective school security measures? What do you think of magnetometers in schools? School Resource Officers? Physical security measures (even to the point of some schools purchasing high-end access control and surveillance systems)? Parent involvement? Drug-free zones? and other approaches that have been taken or considered?