在小学二年级某班的课堂上，同学们齐声朗读课文，唯有小安一人埋头作画。老师见状，愤怒地扯下小安笔下的画纸。此时的老师并不知道，小安作画的原因，竟是为了身为清洁工人的奶奶。一年前，奶奶因车祸伤了膝盖，给她的清洁工作造成不便，小安每天放学后就多了另一份责任，保护奶奶顺利打扫马路，安全回家。 在一次巧合之下，老师得知了实情，为小安的事迹感动，也为自己之前的鲁莽内疚。几天后，在小安的奶奶清扫的那条马路上，多了几个身影——老师带着小安的同学们，举着“大拇指”的标牌，为小安、奶奶以及行人“保驾护航”。

In a class of second grade at a primary school, students were reading text aloud in unison except for Xiao An who was concentrating on painting. Seeing this, the teacher angrily snatched the paper off the desk. At that time, the teacher didn't know that Xiao An was painting for his grandma. Xiao An’s grandma was a street cleaner. One year ago grandma was injured by a car. After she recovered, her knees caused trouble when she was sweeping the road. Therefore, after school, Xiao An went straight to his grandpa, keeping an eye on the traffic so as to protect her from harm. The teachers knew this one day by chance, she was moved deeply and regretted what she did to the boy. Several days later, while Xiao An’s grandma was working , the teacher and Xiao An’s classmates were also there, holding warning boards on which painted a eye-catching thumb-up .They were protecting not only Xiao An and his grandma , but also other pedestrians.