Wells define cognitive development as "the construction of thought processes, including remembering, problem solving, and decision-making, from childhood through adolescence to adulthood." Based on the research article, cognitive development of the students can be improved by social interaction. The findings are applicable and useful for the teachers to apply in the teaching and lesson in the classroom so that it will boost the students' interest in learning.For friendship-based pairings and groupings, it gives many benefits to the students when doing tasks. Basically, students are more prefer to have pair work with friends that they are closed to. This is because they already know each other better and do not feel embarrass or shame to share their thoughts and ideas when interact with them. They also will participate more actively during the interaction and enjoy doing the tasks together. Teachers can obviously observe that they will have better products compared to the acquaintance pairings. However, teachers should not let students to just do the tasks based on friendship and with the same person all the time. Teachers may switch the pairings for every task. The purpose of doing this is actually to let the students get to know other students in the classroom better, besides to foster their relationships. So, when teachers do this frequently, they progressively will get used to each other and will be able to work with another person, even though they are not intimate.