3Johnson, D.W., Johnson,R.T.,& Smith,K. (1991). Cooperative Leaming, p. 16.
4Stevens, R.J.,Slavin, R.E.,& Farnih,A.M.(1991).The Effects of Cooperative learning and Direct.Instruction in Reading Comprehension Strategies on Main Idea Identification Journal of Educational Psychology,Vol.83,No.1,pp.8-16.