This video is a shining example of a teacher at her absolute best during one one the most frightening things that could happen in front of a school. Nursery school teacher Martha Rivera Alanis got her students to the floor when a gang shootout brokeout just outside her classroom and she was able to keep the kids calm by getting them to sing a Barney The Purple Dinosaur song in Monterrey, Mexico. This teacher is a hero. Five people were shot and killed outside the school.