The paper seeks to demonstrate how academic Content Obligatory Language can be potentially organized in teacher talk applying semantic gravity waving from Legitimation Code Theory. The questions asked are: Which concepts do I teach from my discipline in this session? How do I teach these to ensure effective comprehension? Research was conducted for a Content and Language Integrated Learning academic English language programme for undergraduates at a leading Asian University. Three texts as theoretical planning for a teacher input session were composed and provided to students to read. Each text represented different semantic gravity profiles. Students reported which of these texts, if any, was most effectively explaining key concepts from the course. They then provided qualitative comments to substantiate their decisions. Findings indicate that knowledge and use of semantic graving waving can theoretically facilitate student comprehension more effectively and could be a useful tool for planning teacher talk.