The first batch of national standards for digital textbooks for primary and secondary schools will be implemented on November 1, 2022. According to the requirements of the new standard, there is a "limit" on the duration of a single video in digital teaching materials, which is no more than 20 minutes in primary school and no more than 25 minutes in middle school. Moreover, digital teaching materials should be "reviewed by all editors", which has higher publishing quality requirements than general online publications. Since 2017, new policies on the construction of teaching materials, the informatization of education and the prevention and control of myopia among children and adolescents have emerged frequently. The State Administration of market supervision and the National Standardization Administration recently approved the release of three recommended national standards, namely, metadata of digital textbooks for primary and secondary schools, quality requirements and testing methods for digital textbooks for primary and secondary schools, and basic process for publishing digital textbooks for primary and secondary schools. The digital teaching materials for minor groups in primary and secondary schools have higher publishing quality requirements than general online publications. Therefore, the "digital textbook quality requirements and testing methods for primary and secondary schools" put forward that digital textbooks should not have data damage, abnormal error reporting, unable to open, etc. At the same time, the error rate is strictly required. Among them, the text error rate shall be ≤ 0.0025%, while the error rate of pictures, images, audio and video shall be ≤ 0.005%, and the interactive content shall be free of logic errors and major content errors. In order to prevent and control juvenile myopia, the new standard specifically specifies whether digital teaching materials can be "clearly seen" on personal learning terminal display devices and classroom large screens. For example, on the personal learning terminal display device, for the text content of the first and second grades of compulsory education, the display size of the word is the largest, the printing effect of the word ≥ 16p, and the line space of the text ≥ 5mm; For the text content of compulsory education grades 5 to 9 and high school, the display size of words should be ≥ 12p. The digital textbook displayed on the large screen in the classroom has larger words and larger line space between words. Among them, the screen display effect of the text content of the first and second grades of compulsory education should be ≥ 28P words; For the text content of compulsory education grades 5 to 9 and senior high school, the screen display effect should be ≥ 21p words. Moreover, in addition to historical pictures and images, the display resolution of pictures and images in digital textbooks should not be less than 720 pixels, and there are no obvious distortion, blur and other serious distortion problems. The video image shall be of clear quality and free from obvious flickering, jittering, jamming, over bright or over dark phenomena. The new standard specifically limits the video duration. The duration of the content of a single video shall not exceed 20 minutes in primary school and 25 minutes in secondary school. Different from general publications, primary and secondary school textbooks have legal special publishing process requirements. Therefore, the basic process of digital textbook publishing for primary and secondary schools proposes that review and approval is a legal step before the formal publication of digital textbooks for primary and secondary schools, and also a necessary process to ensure the political nature of digital textbooks. Digital textbooks should follow the basic principle of "every compilation must be reviewed". (Xinhua News Agency)