Informatics became a mandatory subject in Japan’s national high school curriculum starting with students entering in 2022. The first cohort educated under this curriculum took the Common Test for University Admissions in 2025, where Informatics was newly added as a subject. Over 300,000 students—more than one quarter of all 18-year-olds—took the Informatics section, highlighting the need for assessment methods that address a wide range of learners.

In light of this need, we launched a five-year project titled Evaluation Methods for Informatics Competence with a Focus on University Entrance Examinations (EMIU). As part of this initiative, two computer-based mock examinations were conducted on the TAO platform: EMIU Informatics Mock Exam Summer 2024 and Spring 2025. These exams contained multiple-choice items designed using Item Response Theory (IRT) alongside general questions in multiple-choice and numerical-entry formats, which reflect those used in current university entrance examinations.

Analysis showed that IRT-based items performed stably across both exams and correlated moderately with general items. Common items enabled cross-cohort comparison, confirming the stability and validity of the assessment framework. These results indicate that IRT-based mock examinations can serve as a strong foundation for designing university entrance assessments in informatics.

The study further contributes to international discussions on large-scale informatics assessment. Adopting an IRT approach demonstrates that computational and programming competencies can be measured consistently across cohorts, supporting national and international efforts to build comparable frameworks.

Future work includes developing detailed item-design guidelines and exploring feedback-based question formats, particularly for programming and problem-solving tasks.