Low-achieving students with behavioural issues often struggle to encounter academic potentials due to difficulties in motivation, concentration, and social interaction. This action research intended to implement effective instructional approaches to improve both learning outcomes and classroom behaviour among these students. The study was led in a secondary school in Malaysia and involved twelve Year 10 Biology students known as low-achieving, very low-achieving, and failing. A qualitative, quasi-experimental method was employed to discover how group discussions and presentations could improve engagement and comprehension of the topic “Effects of Insecticides and Pesticides on the Food Chain and Human Health.” Data were collected through classroom observations, student reflections, and interviews, and were analysed thematically to recognize patterns of learning and behavioural responses. Results exposed that group-based instructional approaches improved motivation, participation, and conceptual understanding among most low-achieving students. Structured collaboration stimulated peer learning, enhanced confidence, and nurtured a sense of belonging within the classroom. However, very low-achieving and failing students sustained to face encounters with focus, communication, and anxiety during presentations, demonstrating the need for more differentiated scaffolding and continued teacher support. Behavioural enhancements such as reduced disturbances and greater task perseverance were observed, reflecting the positive effect of social and behaviourist learning values. In general, the study summarized that collaborative and interactive teaching approaches can efficiently improve both academic engagement and behavioural regulation among low-achieving students when directed by structured facilitation and inclusive instructional design. The results underline the importance of adaptable, student-centred approaches aligned with the goals of inclusive education and Sustainable Development Goal 4, which promotes equitable and quality education for all learners.