Learning objects originated from the object oriented approach in computer science and defined as "any digital resource that can be reused to support learning" (Wiley, 2001), and they are also used in learning and teaching environments. However, literature on learning objects focus on their technical characteristics and metadata. Research on the effects of learning objects on teaching-learning environments especially in social studies lessons is scarce. So, this study examines the effectiveness of learning objects in 6th grade social studies lesson in order to fill the gap between the theory and application of learning objects. The study was pretest-posttest control-treatment group quasi experimental study and was implemented in a primary school in Bolu with 137 students in 6th grade during 24 lesson hours in 8 weeks. At the end of the study, the learning objects developed for the study were evaluated by the students through Learning Object Evaluation Scale (LOES). The findings showed that when learning objects were used with teacher's guidance, academic achievement of students was higher than their achievement in traditional teaching environments. Further investigation revealed that students found LOs beneficial for their learning, highly engaging and well designed.