Quick thinking HERO teacher refused to open door — not even for SWAT

Shanthi Viswanathan,  algebra II teacher at Marjory Stoneman Douglas High School, Parkland, FL That’s her! Yes, the hero-teacher who had the presence of mind to barricade her students inside a classroom and wouldn’t let anyone inside until she knows all of them are safe. When the gunman — who killed 17 people at Marjory Stoneman High