<![CDATA[General Background The implementation of differentiated educational paradigms necessitates comprehensive formative assessment strategies to accurately accommodate diverse student learning needs. Specific Background Senior high school geography entails complex spatial comprehension and geospatial data interpretation, yet educators frequently struggle to identify students' prior knowledge and fundamental errors due to the absence of targeted evaluation instruments. Knowledge Gap Previous developmental research predominantly focuses on creating assessments for exact sciences and languages, leaving a significant void regarding spatial conceptualization evaluation at the secondary education level. Aims This research develops, implements, and evaluates a specialized evaluation instrument designed for tenth-grade students in Denpasar public educational institutions. Results Utilizing the ADDIE framework involving 472 respondents, the study produced 37 validated assessment items with a Content Validity Ratio of 1.00 and a very high reliability coefficient of 0.8762. Analysis of discrimination power revealed 34 high-performing items, while difficulty indices categorized 29 items as easy, seven as moderate, and one as difficult, alongside a comprehensive distractor efficiency evaluation. Novelty This study constructs a uniquely tailored geographic assessment framework that specifically addresses spatial competencies and theoretical interconnections, distinguishing it from conventional exact-science evaluations. Implications The resulting valid and reliable instrument provides educators with a practical tool to accurately identify individual learning obstacles, facilitating targeted and differentiated instructional strategies within modern curricula. Highlights The ADDIE framework successfully yielded thirty-seven reliable assessment items for spatial comprehension evaluation. Statistical analysis demonstrated a very strong reliability coefficient of 0.8762 among the surveyed respondents. Item evaluation revealed functional distractor efficiency and distinct discrimination power across various difficulty levels. Keywords Formative Assessment; Spatial Comprehension; Item Reliability; Distractor Efficiency; Differentiated Instruction]]>
