The study of online inquiry competences (OIC) is an important topic on the information literacy (IL) field. Most of the work has been focused on higher education and high-school students, while less has been done regarding primary education. In this work we investigate the effects of an OIC teaching intervention on search performance of a large group of sixth graders from Finland. Our preliminary results show significant improvements in search performance on the intervened group of students compared to a control group when working on a science research task. This work shed light about the potential benefits of a particular approach to develop OIC on elementary school students.