<![CDATA[Science learning for deaf students requires appropriate methods, media, and assessment tools to address their limited vocabulary and diverse learning needs. Accurate measurement of learning outcomes also requires testing instruments that reflect students’ actual abilities. This study aimed to evaluate deaf students’ abilities in science learning on light and its properties through the student teams achievement division (STAD) model using a multiple-choice test developed based on the two-parameter logistic (2PL) item response theory model, which estimates ability from item difficulty and discrimination. The study involved 32 deaf students at the elementary level from six special schools (SLB-B) in several regions of Indonesia. An experimental method was employed, and data were analyzed using a one-sample sign test with the minimum mastery criterion as the reference value. The results showed that the abilities of most deaf students in understanding light and its properties had not reached the minimum mastery criterion, indicating that basic concepts had not been optimally mastered. Differences in learning outcomes across schools may reflect variations in learning quality, student abilities, additional disabilities, and the implementation of the STAD model. These findings highlight the need to improve instructional strategies and develop assessment instruments that are better aligned with the characteristics and learning needs of deaf students. The results provide a reference for developing more responsive learning and assessment systems in special schools]]>
