School education is the most important channel for knowledge acquisition. However, what the educators have long been interested in is teaching methodology rather than knowledge itself. To solve the problem of what Karl Maton calls “knowledge blindness”, scholars of both SFL and social pedagogy have made some successful experiments, yet, as Jim Martin points out that further efforts are still needed to find more effective ways to help students to know what knowledge is and how knowledge can be accumulated. This paper attempts to achieve this goal by looking at how power words, power grammar, power composition and intertextuality work in the process of knowledge building in academic discourse.