The purpose of this study was to investigate the effects of learning achievement by comparing the group based on Co-op Co-op learning and the control group. For this purpose, the experimental study on the unit of making plain food was achieved with 84 students(6th grade 2 classes) in K-elementary school in Pa-ju city. The Co-op Co-op learning model (Kagan) was applied to the experimental group, and the traditional small-group method to the control group. For this experiment, nonequivalent control group pretest-posttest design was applied 10 times during 6 weeks.The results were as follows; First, There was not significant difference of learning achievement as the results of the pre test. So the results has been showed that the two groups are same level of cognitive and affective domain. Second, There were significant differences of achievement of cognitive and affective domain as the results of the post test. But there were not of psycomotor domain. Third, As the pre and post test, there exists significant differences of learning achievement(cognitive and affective domain) in the experimental group, but the control group was not. In addition, the learning achievement (affective domain) of the experimental group has been showed significant difference about eating between meals, nutrition, etc. But the control group was not. Based on these results, it is concluded the Co-op Co-op learning method is more effective than the traditional small-group learning method in learning achievement of the unit making plain food.