Expand knowledge: CETV No.4 was born on May 19, 2003. In order to fight against SARS and solve the worry that primary and secondary school students are forced to suspend classes, China Education Television, with the care of the Party and the state and the strong support of the Ministry of Education and the State Administration of Radio, Film and Television, has been allowed to set up temporary TV channels to offer "air lessons" for students who have suspended classes at home. On June 5438+February, 2008, it officially became a satellite TV channel. On March 2, 2009, it was officially launched. 20 1 265438+1October1,the air classroom channel was completely revised, and the theme of "China literature record" was put forward. On February 17, 2020, the national primary and secondary school network cloud platform was opened. The platform resources include epidemic prevention knowledge, red education resources, special education resources, and curriculum resources from primary schools to ordinary high schools. The course time is generally about 20 minutes.