In an anti-violence exercise at a primary school in Jinan city, capital of East China's Shandong province, a teacher and students try to stop an intruder from entering a classroom, on Dec 18, 2012. The exercise was held four days after a brutal knife attack at a primary school in Henan province, leaving 22 pupils injured. [Photo by Zheng Tao/Asianewsphoto]

In an anti-violence exercise at a primary school in Jinan city, capital of East China's Shandong province, a teacher and students try to stop an intruder from entering a classroom, on Dec 18, 2012. The exercise was held four days after a brutal knife attack at a primary school in Henan province, leaving 22 pupils injured. [Photo by Zheng Tao/Asianewsphoto]