The main scope of this research is about the unit “Volume” of the fifth grade in primary school. The theory of this research is to take the Bayesian networks as a reasoning tool. According to the teaching goals、sub skills and error types of the questions, Bayesian networks can be a reference tool applying in Math computer diagnostic tests in primary school. The error types of students would be diagnosed through this test and it can provide teachers with a reference tool in teaching. The results of the research are as the followings: 1. To build an automatic scoring and analyzing error types questions on-line computer diagnostic test. The goal of the research is to create an automatic scoring and analyzing error type questions on-line computer diagnostic test based on constructed response questions. We can realize the pupils’ test results、responses and error types through the test. 2. Effectiveness of computerized constructed response questions test. The research analyzes the error types of the constructed response questions. The average differential rate of the four questions is 97.14％. Therefore, the differential rate of the automated analysis of constructed response questions is excellent. 3. Evaluate the effectiveness of Bayesian network and compare with multiple-choices questions and add with the constructed response questions. The research combined with Bayesian network、sub skills and error types is to design a tool examining multiple-choices questions and constructed response questions. Through Matlab, it can analyze the differential rate. The outcome shows that Bayesian network works better in exams that with constructed response questions than only with choices.
