Why is the beginning of each chapter in bold?

The beginning of each chapter starts with a conversation between adults involved in the battle school. In the novel's first chapters, we are unaware of the men discussing Ender and his future. These conversations are secret, and Ender is unaware of the speakers' actions. Chapter Fifteen, also opens with a conversation between Graff and Anderson, but the typeface is longer bold, thus making it a part of the "open" rather than "secret" text.