After-class teachers, according to the teaching situation in the classroom, collate and sum up the key points, difficult points, difficult problems and problem-solving skills of each chapter, and make a micro-video or PPT format and upload it to the wechat platform, so that students can use the fragment time to browse and study. Teachers can also upload important points of knowledge in class to wechat platform in the form of pictures or videos, so that students can watch it again and again after class according to their own situation, knowledge internalization and construction.