What is Effect Size

Do media influence learning? This is a historical debate in the field of educational technology, which started when Clark (1983, 1994) argued that media are “mere vehicles” and it is the content and pedagogical methods that are the “active ingredients” influencing student learning. Others (e.g., Kozma, 1994; Cobb, 1997) disagreed and argued that special media attributes can make certain types of learning more effective or cognitively efficient. In this chapter, I will first review the key arguments for and against media effects in distance education (DE). I will then review several meta-analyses that attempted to analyze the effects of media and pedagogy based on quantitative syntheses of the empirical research in DE. Finally, I will discuss directions for future research.