Abstract: With the gradual update of the Internet industry,online learning and online classes have become an indispensable part of most families.The development of computer-assisted learning systems has led to an increase in the research on knowledge diagnosis,in which students' performance in coursework can be predicted over time.Due to the urgent need for educational applications with knowledge graphs,this paper developes a system called KGIRT.Its specific functions are as follows.First,it constructs a knowledge map (KG) for junior and high school mathematics courses.Compared with the traditional education domain know-ledge map,the mathematical subject knowledge map created in this paper focuses on knowledge itself,not limited to grades and books.It associates the mathematics knowledge points of junior high school and high school in the same knowledge graph accor-ding to the logical relationship,and students can judge the mastery of relevant knowledge points by using this system.Second,it sets the difficulty of the topic in the system diagnosis model.And by introducing the expert method into the diagnosis model,it makes the judgment of the difficulty of the topic more accurate,more objective and more systematic.Third,it combines the knowledge map with the cognitive diagnosis model,and the cognitive diagnosis model based on the knowledge map is used.Charts and matrices indicate the current status of student knowledge.Finally,based on the joint application of the knowledge graph database Neo4j and cognitive diagnosis model,an online learning WeChat applet KGIRT is developed,which realizes the transformation from theory to application.

Key words: Cognitive diagnosis model, Graph database Neo4j, Knowledge graph, Teaching assistant system