Highlight notes. Before constructing a topic sentence, an ethnographic researcher gathers observations, interviews and research on a particular population. To begin developing the topic sentence, read through all notes and personal reflections garnered from these different areas. Highlight the most relevant or important ideas, moments and patterns.
Organize important ideas. From the highlighted sections, make a list of the most important ideas or moments from the study. Put them in a list on the computer or write them by hand. Copy the list, then cut the ideas apart and sort them into groups or patterns. Do this more than once so you begin to find the most important issues and observations that will form the essay's foundation.
Choose the most important idea. From this list and grouping of ideas, choose one that is most interesting to you, the researcher. Try choosing one to which many of the other ideas can be connected, or that touches several areas of your observations. This idea should be a main conclusion of your research -- one of the answers to the question you set out to study.
Develop a working topic. From this most important idea, develop a sentence that makes a claim about results of the research you have done. This sentence should be a summary and an assertion. For example: "The homeless of Anytown support one another in a way that substitutes for family connections in their lives." Likewise, your research may lead to you this topic sentence: "The homeless in Anytown lead solitary lives with few, if any, personal connections that might give them support, help or hope."
Evaluate the topic sentence. Since the topic sentence provides the structure for your entire ethnographic essay, test it for validity before deciding to use it. Make sure it meets the three criteria outlined by Booth, Colomb and Wilson in their research on writing critical claims: It should be substantive, contestable and specific. "Substantive" means that is more than just telling what a paper is about.The topic sentence should attract interest with a unique claim. "Contestable" means that is not simply an observation or a restating of obvious facts. Instead, it should provide new information or insight, a new way of seeing or understanding an issue. "Specific" means that the claim is narrow and clear, giving an idea of what kinds of evidence and arguments will follow to support the claim.
Finalize the topic sentence. If the topic meets all three criteria for evaluation, then polish the sentence's grammar and structure so it can be used as the foundation of your ethnographic essay. All sections of the essay should support, describe or provide evidence for the topic sentence.