Classroom instructional management plays a vital role in fostering students' behavioural engagement, particularly in vocational high school settings where practical application and focus are crucial. This study aims to investigate the specific classroom instructional management strategies employed by an English teacher to enhance students' behavioural engagement and to explore how these strategies influence the level of engagement during EFL classroom activities. Employing a qualitative case study design, the research was conducted at a State Vocational High School in Sukoharjo, involving one English teacher and five selected students. Data were collected through classroom observations and in-depth semi-structured interview, which were subsequently analyzed using thematic analysis. The findings reveal that the teacher implemented a "Hybrid-Adaptive Model," integrating Structured Direct Instruction—such as clear goal-setting and explicit grammatical scaffolding—to reduce cognitive load, alongside Dynamic Interactive Instruction, including mandatory demonstration, peer tutoring, and digital gamification, to drive active participation. Consequently, these instructional management strategies elevated students' behavioural engagement from a medium to a high-moderate level, shifting them from passive compliance to guided active involvement by mitigating the social cost of participation. The study concludes that combining structured pedagogical management with interactive dialogic learning provides a highly supportive environment that minimizes disengagement, although achieving fully autonomous, self-regulated student engagement remains a pedagogical challenge.