As teachers, to ensure that both pair work and group work activities are effective to the students in the learning, teachers must play their role as facilitator. Teachers just give explicit instructions to them before starting their pairings or groupings. Teachers must not spoon-feed them too, but let them responsible for their own learning, so that they will become independent learner and practice student-centered learning style. Capuzzi (cited in Kelman (1963)) proposed that group work helping members to overcome feelings of isolation, develop hope for increased adjustment, learn to accept responsibility, develop new relationship skills and enhance commitment to change.In addition, during the tasks or activities, teachers have to provide questions or tasks that can train students to respond correctly as well as which can facilitate students' cognitive development. The questions also must have different level of difficulty which can challenge their thinking. When students are instructed to find the answers, they will discuss the questions and interact by arguing their own ideas to find the correct answers. So, when students are actively participating in the tasks, they will share the pre-requisite knowledge among them and at the same time build up their knowledge. There will be collaborative learning and cooperative interactions between the students too.As a conclusion, cognitive development engages the students in the process of gaining information. It also requires students to cooperate and interact each others to find solutions to problems. These cooperation and interaction will make the students to enjoy learning and they will look forward to learning the subject. Besides, they will progressively improve in their academic performance and they will become creative and critical students. For teachers, their teachings will be effective and this will create enthusiasm for teaching the students. In addition, it will boost teachers' self-esteem because effective teaching takes place in the classroom.