A broad topic has literally thousands of articles on it, and you won't be able to adequately cover it in your blog. It will be far easier for you to research and write your blog if you develop a strong, focused research question or topic:
Do some exploratory research on your topic idea, in your course textbook, class notes, and Mardigian Search to identify specific issues, arguments, and analytical approaches in your research area and then identify possible relationships between them.
Ask yourself questions about your topic idea. What concepts, issues, or other aspects of this topic interest you? What have people said about it? What gaps, contradictions, or concerns arise as you learn more about it? What relationships are there between different aspects of the topic?
Focus your topic: Use the information from your exploratory research to identify a few of the specific aspects that interest you and then use the questions you had about those to focus your blog topic.
Choose a current topic: Your goal is to summarize and evaluate current findings of an area of research. Pick a research topic about which articles are continuing to be published. Avoid defunct or little-known areas of research.
Write about what interests you: Professors want students to write about topics that they care about. If you're interested in the topic, it will be more fun for you to write your blog and probably more fun for your professor to read it, too.
Ask Dr. McKenna for feedback on your research topic or question.
