The core concept of the fifth industrial revolution is the harmonization of humans and machines, emphasizing a human-centric approach where humanoid robots are designed to interact with humans or work and collaborate with humans in human-centric environments. However, full-size humanoid robots are highly expensive, which diminishes their suitability for application-specific activities such as teaching in classroom environment. Researchers in numerous studies have been found facing challenges regarding the development costs and complexity while designing the mechatronics. This article addresses the gap by proposing a cost-effective design for a humanoid robot (Dbot) capable of performing specific functions such as talking, moving, shaking hands, and communicating with humans, which can be utilized in activities aiming classroom teaching. With 31 Degrees of Freedom (DOF), Dbot demonstrated human-like motion relying on a lightweight and rigid mechanical structure made of aluminium followed by a building process utilizing low-cost hardware sourced from local and commercially available sources. The design with its multistage development went through rigorous testing and optimizations. A functional Dbot was tested with students of specific age group at Daffodil International School and College, and its performance as a classroom teacher or instructor was evaluated based on response, accuracy, command recognition and other criteria. These tests and overall analysis resulted that Dbot with its lightweight and low-cost design can successfully perform with students in classroom, with a 95% accuracy in voice recognition along with appropriate gesture and interaction representing significant potentials for the advancements in task specific application of humanoid robots.