The study investigated the impact of active learning strategies such as constructivist teaching strategies, activity-oriented lessons, asking thought-provoking questions and discovery learning on students' behavioural and cognitive engagement. The study employed a pre-experimental design type of one-group pretest-posttest design. Data were collected using a five-point Likert scale from 25 class IX students. The same Likert scale question with a 5 scale was employed before and after a four-week intervention of active learning strategies. The findings revealed that after the implementation of active learning strategies students' behaviour and cognitive engagement have significantly improved. Students exhibited improved enthusiasm, motivation and active participation in the class consequently leading to higher level of behavioural engagement. Furthermore, students showed an improved willingness to tackle challenging tasks in the class, thereby improving cognitive engagement. By facilitating better student engagement, students participate in challenging tasks and exhibit motivated attitudes during the teaching and learning process. The study is significant in understanding the positive impact of active learning strategies on behavioural and cognitive engagement. The study primarily recommends that teachers in Bhutanese middle secondary schools implement active learning strategies to facilitate student engagement. Active learning strategies, such as activity-oriented lessons, asking thought-provoking questions, and constructivist teaching strategies lead to interactive teaching and learning processes. However, the study was limited to one school and focused on only physics classes, and the sample size was relatively small.