From grammar to sustainability: A corpus-informed pedagogical model (GSIC) based on African Leaders' UNGA-2025 English speeches.

This study investigates how African leaders linguistically construct sustainability discourse in their United Nations General Assembly (UNGA-2025) speeches and demonstrates how these linguistic patterns can be transformed into a pedagogical model for Education for Sustainable Development (ESD). A 50,644-token corpus of 21 African leaders' UNGA-2025 English speeches was analyzed across five linguistic levels-lexical, morphological, syntactic, pragmatic, and discourse-using a mixed quantitative-qualitative approach. Results show that sustainability meaning is built predominantly through lexical items (48.6%) and discourse organization (26.5%), supported by pragmatic strategies (16.5%) emphasizing urgency and collective agency. Key grammatical resources-including modal verbs (must, should), conditional statements, passive constructions, collective pronouns, and problem-solution sequencing-map systematically onto sustainability competencies: normative, systems-thinking, interpersonal, anticipatory, and strategic. Strategic and interpersonal competencies dominated, reflecting Africa's emphasis on governance, multilateral partnership, innovation, and climate action. Based on these mappings, the study proposes the Grammar-for-Sustainability Instructional Cycle (GSIC), a five-phase task model (noticing, analysis, transformation, production, reflection) that operationalizes authentic UNGA discourse for language instruction. GSIC supports simultaneous development of grammatical control and sustainability competencies, positioning grammar as purposeful social action. The findings contribute a novel linguistic-competency mapping framework and demonstrate how corpus-informed pedagogy can enrich ESD, particularly within African English language education.