李永乐老师

Li Yongle (Chinese: 李永乐), better known online as 李永乐老师 (lit. Mr. Li Yongle, Teacher Li Yongle) is a Chinese YouTuber. He is known for his eductional videos and popularization of science videos.

Backstory
Li Yongle was graduated from Tsinghua University in 2009. According to a speech delivered in Tsinghua University by him on October 10, he later became a physical teacher in The High School Affiliated to Renmin University of China.

Going Vital
On April 2017, the official Sina Weibo account of People’s Daily reposted his video titled 闰年是什么？清华学霸老师让你真正弄明白, which contribute his vital.