MONROE, Conn. – On a tour Wednesday of his daughter’s new school, Vinny Alvarez took a moment to thank her third-grade teacher, who protected the class from a rampaging gunman by locking her classroom door and keeping the children in a corner.

Alvarez was one of many Sandy Hook Elementary School parents expressing gratitude to the teachers during an open house at their school in the neighboring town of Monroe, where their children are resuming classes today for the first time since the Dec. 14 shooting that left 20 children and six educators dead.

Alvarez said each student received a gift box with a toy inside and he expressed thanks to the teacher, Courtney Martin, who kept her door locked until it was safe to leave the building.