У вашего броузера проблема в совместимости с HTML5
References: Pacific Lutheran University. (n.d.). Negligence and the duties of a teacher. Retrieved February 3, 2016, from https://community.plu.edu/~labsafe/doc/negligence-duites.pdf Sadker, D., & Zittleman, K. (2013). The teachers, schools, and society (10th ed.). New York: McGraw-Hill.