The traditional method is being widely used in teaching of science at elementary level in Pakistan despite of knowing its advantages and disadvantages. This study was aimed at investigating effectiveness of traditional and heuristic methods of teaching science at elementary level. The experimental study was delimited to Punjab. Two schools-one urban and other rural, were selected on convenient basis to conduct the experiments. One of the experiments was conducted in urban area of district Lahore, while the other was conducted in the rural area of district Jhang. In this study, an achievement test was used as an instrument which covered four major areas of the study. Among 90 students of 6th class, 60 students were selected randomly in rural school and 60 students out of 126 students were selected in urban school. After then, 60 students of 6th class from each school were divided into two equal groups having almost similar level of learning achievement. Experiment 1 (rural school) was conducted in September, 2009 while the experiment 2 (urban school) was conducted in April-May, 2010. Each experiment was comprised of a control group (taught by traditional method) and an experimental group (taught by heuristic method). Semistandardized lesson plans and science kit were used for teaching to the experimental groups using activity based teaching learning model. Each experiment lasted for eight weeks with five days teaching the subject of science to class VI. Pre-test post-test equivalent group design was used. In the beginning of the experiment, pre-test was conducted for the groups in rural and urban schools. Two teachers having similar educational qualifications and teaching experience were selected to teach these two groups including researcher. Data was analyzed using SPSS. The statistical techniques used to investigate the effectiveness of control and experimental groups in rural and urban areas were mean, standard deviation, co-efficient of variance and t-test. It was found that the performance of experimental groups, both in rural and urban schools was better than the performance of control groups, which shows the scope and significance of heuristic method to teach science at elementary level. It was also found that the achievement level of experimental group was better in all four content areas of test i.e. Characteristics of living and nonliving thins, Cell a unit of life, organization of life and environment. It was also found that the achievement level of experimental group students was better in all three ability skills i.e. Knowledge, Comprehension and Application. On the basis of findings, conclusions and recommendations were made accordingly.