Some analysts believe that the success of Khan Academy is a protest and challenge to the current education system. According to YouTube statistics, Khan's courses are more popular than the free online courses made by his alma mater, Massachusetts Institute of Technology. Many online courses in universities only film the process of professors' class, emphasizing "teaching"; Khan's teaching videos highlight the process of "learning". Some media pointed out that the "Khan model" makes people question many "two truths" of higher education-whether only experts are the best teachers, and an hour or so is the most appropriate for each class ... In American education, there are also video teaching classes, but the effect has not been good, and students are all facing a computer alone, and communication with teachers is limited. Today, two schools in California, USA, tried out the teaching video of Khan Academy in the fifth and seventh grades. Students watch videos at home and teach themselves. Teachers answer questions in class and help students finish their homework. Khan said that this is exactly what he wants to see: "My goal is to make a video course that everyone is willing to follow. I am very happy to see people enter universities or get good grades with the help of Khan Academy. " Khan's next goal is to produce all the courses from kindergarten to high school and some university courses, such as computer science and electronic engineering, in the next five years. When nicole Nisim, a freshman at the University of Florida, was trapped in trigonometry, she found a video of "Teacher Khan" explaining trigonometry on YouTube instead of asking her teacher or classmates. After reading it several times, the problem was solved. The whole process was convenient and quick, and it didn't cost her a penny. This Khan teacher is Salman Khan, currently the "most popular teacher" on the Internet. Since 2004, he has produced more than 2,300 video tutorials, covering everything from mathematics to the Vietnam War. Statistics show that up to now, 56 million people have watched his "teaching video".