Besides that, when conducting pair work, teachers should consider students' ability level; low, middle and high. Teachers should not place students with the same ability together when doing pair work task. For example, do not let low ability students working together because they are slow learners. Teachers may notice that they will feel demotivated, will be left behind and the product of the work is less quality when compared to the high ability pairings. Next, teachers may realise that the low ability pairings have lower performance when doing task. Conversely, if teachers put the students with different abilities together in a group, the high ability students will act as tutors which help the low ability students to understand the tasks given. So, when they explain and discuss the tasks together, the low ability students will feel comfortable to ask any questions together. Thus, teachers should identify students' ability, so that they can conduct effective teaching and learning in order to enhance students' cognitive development.Teachers too should encourage their students to combine and mingle with different sex during the pairings and groupings. It is good to combine boys and girls for a task, since boys and girls have different level of thinking. Basically, girls are more hardworking and more serious in their studies compared to boys who are more playful and do not really focus in their studies. When teacher mix them, boys will be influenced by the girls' attributes and because of that, they are able to focus on their studies instead of playing games or doing unwanted things during the lessons. Furthermore, when they work together, they will gain each others' knowledge as boys are excel in Mathematics and Science subjects compared to girls who are better in reading and writing competency especially in language subjects. Hence, this will improve students' cognitive development.