Empirical Evidence for the Social Cohesion Perspective : The achievement outcomes of co-operative learning methods that accentuate task specialisation are imprecise. Research on the original form of Jigsaw has not found positive effects of this method on student achievement in general (Slavin, 1995). However, students have limited exposure to material other than that which they studied themselves, so learning gains on their own topics may be compensated by losses on their group-mates' topics. In contrast, there is evidence that when it is well implemented, group investigation can significantly increase student achievement (Sharan & Shachar, 1988). In studies of at least four weeks' duration, the Johnson's (1994) methods have not been found to increase achievement more than individualistic methods unless they incorporate group …show more content…
Cognitive perspectives imply that mutual interaction between students with “the mental processing of the information rather than with motivations” (Slavin, 1996 : 48) will improve students’ academic achievement. The two perspectives, namely, cognitive development and elaboration are discussed in the following paragraphs to examine comprehensively their effects on student learning. The two cognitive perspectives explained in the following paragraphs focus on the interactions among groups of students, holding that these interactions themselves lead to better learning and thus better achievement. 3. Cognitive Developmental Perspective : A fundamental assumption of the cognitive development perspective driven by theories is that reciprocal interaction among children around suitable academic tasks creates growth in the knowledge of concepts and critical skills (Slavin, 2011). Vygotsky’s notion of the Zone of Proximal Development (ZPD) is meaningful to learning. Such learning happens through interaction with each other in the ZPD. Vygotsky (1978) defines the ZPD as the distance between the actual developmental level as determined