<![CDATA[Students experience difficulties in solving non-routine problems, particularly when interpreting information, connecting spatial elements, selecting strategies, carrying out procedures, and evaluating their answers. This condition indicates the need for a summative assessment that measures not only final outcomes but reveals students’ problem-solving processes. This study aimed to develop a valid and practical summative assessment based on Polya’s problem-solving stages and to describe its potential to elicit students’ mathematical problem-solving processes. The study employed development research using Tessmer’s formative evaluation procedure, which included preliminary analysis, self-evaluation, expert review, one-to-one evaluation, small- group evaluation, and field testing. The participants were eighth-grade students from a junior high school in Palembang who had studied polyhedral geometry. Data were collected through validation sheets, students’ written responses, response questionnaires, and interviews. The data were analyzed descriptively to determine content, construct, and language validity, assess practicality, and identify students’ problem-solving stages. The expert review results showed that the developed assessment met the validity criteria after revisions were made to its content, construct, and language aspects. The small-group evaluation yielded a practicality score of 85%, categorized as highly practical. Written responses and interviews showed that the assessment was able to elicit the stages of understanding the problem, devising a plan, carrying out the plan, and looking back, although students still required support in planning and answer verification. The assessment can be used by teachers to evaluate students’ problem-solving ability after instruction. The originality of this study lies in integrating Polya’s problem-solving stages, polyhedral geometry, and summative assessment.]]>
