Final answer:
Topic sentences are crucial for setting the main idea of a paragraph, which can be supported by reasons, illustrations, explanations, or evidence. They frame the subject and guide the subsequent development of the paragraph, whether through narrative, chronological order, or cause-and-effect relationships.
Step-by-step explanation:
Topic sentences serve as the focal point of a paragraph, conveying the main idea that is then elaborated upon with details, evidence, or examples. A topic sentence typically sets up either a reason for its claim, an illustration to support it, an explanation of its argument, or evidence to demonstrate its point.
For example, in discussing the effects of an oil spill, a topic sentence might be: "Because an oil spill occurred off the coast of California, the fur and feathers of animals became dangerously matted, waterways were damaged, and the cost of maintaining a clean environment skyrocketed." This sentence establishes the cause - the oil spill - and the subsequent effects outlined in the following sentences. Similarly, in a topic about the pandemic: "Because of the pandemic, gas consumption dropped, indoor dining at restaurants declined, and online shopping rose."
When giving feedback on clarity and coherence in paragraphs, one might comment with a peer review that a paragraph requires a topic sentence and further development if it lacks a central theme or sufficient explanatory details.
Finally, when structuring paragraphs with topic sentences, it's important to remember that the paragraph should open with the main topic, followed by sentences that develop this topic chronologically, through cause-and-effect reasoning, or by building upon a narrative.