Evaluating and optimizing Japanese tutor system featuring dynamic question generation and interactive guidance

We are developing a new CALL system to aid students learning Japanese as a second language. This system is designed to allow students to create their own sentences based on visual prompts, receiving feedback based on their mistakes. The questions are dynamically generated, resulting in a large variety of challenges. The students may choose to receive guidance in order to complete each task, selecting the level of help that best suits their needs. A scoring system is also incorporated, which awards a grade to students based on the errors made and hints used. The trial of the system has been conducted with twenty one students, providing the statistics of actual errors and hint usages. With these data, we have trained the weights of the scoring system by taking into account the impact of each issue on the proficiency of the students. The validity of the estimated score is generally confirmed by predicting the proficiency of the students.