In private journals, students take personal risks by writing about their own experiences. For example, Mr. Foster said, in a discussion of whether the American dream still exists, a student writing in a private journal might reflect on her family’s socioeconomic class or financial struggles. But she might hesitate to share something so personal in a public setting. On public blogs, where their classmates will see and perhaps even comment on a post, students engage in more intellectual risks, crafting complex arguments on what are often — especially in sociology courses — controversial issues, Mr. Foster said.