The National Science Education Standards emphasize a goal that students should achieve scientific literacy, which is defined as the knowledge and understanding of scientific concepts needed in daily living. Scientific literacy enables people to not only use scientific principles and processes in making personal decisions but also to participate in discussions of scientific issues that affect society. Understanding scientific knowledge and processes contributes in an essential way to these skills. The economic productivity of society is related to the scientific and technological skills of the people. The results of this study indicate that students in the student-centered STS sections achieved significantly better than students in the teacher-directed STS sections in terms of understanding and use of process skills, use of creativity skills, development of more positive attitudes; and the ability to apply science concepts in new contexts.