In today's world, dominated by technology, science, and innovation, education is entrusted with a new and responsible role—not only to transmit knowledge, but also to develop competencies in students that will ensure their confidence and success in the future. Among the most essential of these are STEM competencies—skills and attitudes related to science, technology, engineering, and mathematics. The need for their development is indisputable and requires not only appropriate educational content and approaches, but also adequate methods for their measurement.

The development of STEM competencies is of great significance for both the personal and professional growth of students. In a world where emerging professions are closely linked to technology, programming, data science, and innovation, the cultivation of logical thinking, problem-solving skills, and teamwork is indispensable. By applying a STEM-based educational approach, students are engaged through practical and project-based activities, which foster motivation for learning and stimulate social involvement and critical thinking about the world around them.

A crucial emphasis must be placed on the necessity for a clear and well-structured metric for assessing STEM competencies. Without measurable indicators, it is impossible to evaluate the effectiveness of the educational process or to monitor students’ individual progress. The systematic implementation of a comprehensive assessment system not only allows for better adaptation of the learning process to students’ needs, but also strengthens trust in the overall quality of STEM education.

STEM education at the different stages of schooling—primary, lower secondary, and upper secondary—has its own specific characteristics. For effective assessment of STEM competencies at each stage, it is essential to apply metrics tailored to the respective developmental level. At the primary level, where students acquire knowledge through play, tasks, and experiential learning, observation-based metrics are more appropriate, along with participation in activities, basic experiments, and modeling. In the lower secondary stage, students begin to develop logical reasoning and are capable of solving more complex tasks, which makes it possible to include projects, technical activities, and the use of software tools. At the upper secondary level, where students can think abstractly, analyze, and design their own projects, the assessment metrics should incorporate evaluation of innovation, interdisciplinary thinking, and the ability to present and justify ideas.

The present article presents the results of experimental work related to the introduction of a STEM metric in Bulgarian schools. As part of a project funded by the Bulgarian National Science Fund, a framework for adaptive assessment of STEM competencies for students from grades 1 to 10 has been developed. The assessment tools were piloted in schools with a demonstrated effective implementation of STEM approach in the educational process. The specifics of the STEM domain vary across schools — both in terms of scientific knowledge areas and educational stages. The developed metric system evaluates academic knowledge and skills, metacognitive STEM competencies, STEM culture, and the level of development of personal competencies.

The article presents results and analyses from the experimental work conducted. Conclusions, findings, and recommendations are formulated.

Keywords: STEM competencies, STEM education, competency assessment, adaptive metric system, metacognitive skills