Cooperative Learning (CL) includes all structures and processes of teaching-learning where students achieve learning goals by helping each other in a small social setting. This paper provides an exploration of the effectiveness of cooperative learning technique JIGSAW in the teaching of Mathematics for school students of XII standard. The Post-test only Control Group Design followed by a systematic random sampling technique was adopted to select the sample for the present study. The experimental group and Control group of 20 students each were formed, out of 87 Normal and Bright Normal intelligent students. Experimental group and control groups were instructed with cooperative techniques JIGSAW and Traditional Method respectively. A post-test on Constructivist Learning Environment (CLE) was administered. The findings revealed that JIGSAW cooperative technique is better in developing Constructivist Learning Environment than Traditional Method.