<![CDATA[This study was motivated by the limited availability of diagnostic assessment instruments that teachers can use to identify indications of dyscalculia among junior high school students based on linguistic skills, perceptual skills, and attentional skills. This condition highlights the need to develop an instrument that can assist teachers in systematically identifying mathematics learning difficulties as a basis for providing appropriate educational support according to students' learning needs. This study aimed to develop a valid, reliable, practical, and effective dyscalculia identification test instrument for seventh-grade junior high school students. The study employed a Research and Development (R&D) method using the ADDIE development model, consisting of Analysis, Design, Development, Implementation, and Evaluation. The research participants included expert validators, mathematics teachers, and 32 seventh-grade students at SMP Negeri 3 Bukittinggi selected through purposive sampling. Data were collected through validation sheets, tests, practicality questionnaires, interviews, and documentation. The data were analyzed using quantitative descriptive analysis, item quality analysis, and qualitative data analysis. The findings revealed that the developed instrument achieved a validity level of 77%, categorized as valid, a reliability coefficient of 0.916, categorized as very high, and a practicality level of 78%, categorized as very practical. The effectiveness assessment using the stanine method showed that, among 32 students participating in the field trial, 3 students were classified as being at risk of dyscalculia. Further analysis of the three identification aspects indicated that 2 students showed indications of dyscalculia, while 1 student experienced general mathematics learning difficulties. These findings indicate that the instrument can help distinguish students showing indications of dyscalculia from those experiencing general mathematics learning difficulties. Therefore, the developed instrument is suitable for use as an initial screening tool in mathematics diagnostic assessment to support teachers in identifying students' learning needs and designing appropriate instructional follow-up activities.]]>
