This study examines the effectiveness of learning CTL (Contextual Teaching and Learning) on the matter of biotechnology, namely making nata de coco. The method used is the method of quasi-experimental research subjects students take one SMAN in Cianjur. The study used a descriptive analytic techniques. The effectiveness of learning is determined based on the following criteria: 1) the significance of the thoroughness of learning outcomes, in terms of mastery of concepts is achieved; 2) the ability of inquiry indicated during PBM; 3) interaction pattern formed during PBM, namely the interaction patterns are symmetrical, asymmetrical shifting, and asymmetrical, adapted from Johnson & Johnson (1975). From these results it is found that it turns learning model is effective with the fact that support, namely: 1) The study results turned out to be significantly better than the complete learning criteria (Zscore = 5.69); 2) the ability of scientific inquiry at all emerges with the ability greatest scientific investigations (24.45%) and the lowest in the ability to develop descriptions, explanations, predictions and models based on evidence (10.70%); 3) interaction pattern formed is symmetrical patterns of interaction (50.72%) and the shifting asymmetric (49.36).