The study explores the concept of pedagogical expediency as a system-forming criterion of
sustainable didactics, addressing the need for a new educational paradigm in the context of global ecological
and cognitive challenges. Traditional linear didactics is shown to lose semantic relevance under conditions
of ecological crisis, cognitive overload, and transformation of human subjectivity. Methodology. Within the
framework of Systemic-Structural Didactics (SSD), a multi-level model of pedagogical expediency was
developed, encompassing biophysiological, psychological, social, and ecosystemic levels. The study applies
structural modeling, content analysis, and interdisciplinary synthesis to design diagnostic and developmental
tools for ecological-chemical education (ECE). Results. The research formalizes the SSD architecture, which
includes ontological, functional, and operational contours, ensuring systemic alignment of educational values,
content, and methods. The proposed matrix of correspondence between levels of expediency supports the design
of sustainable learning processes. The model of ecological metacompetence (EMC) is presented as an integrative
educational outcome that unites cognitive, ethical, behavioral, and adaptive dimensions. Scientific novelty. The
study introduces and substantiates the concept of ecological metacompetence and integrates it into the SSD
framework as a key indicator of sustainable and ethically grounded learning. The transition from a utilitarian to
an ontological logic of pedagogical activity is theoretically justified. Practical significance. The proposed SSD
based model can be applied in the design and evaluation of interdisciplinary courses, particularly in ecological
and chemical education, ensuring coherence between knowledge acquisition, ethical reasoning, and sustainable
behavior.