Titles and subtitles often give a clear indication of the main idea. For example, in a passage titled "The History of the Internet," the main idea is likely to be about how the Internet came into being and developed over time.
Opening paragraphs often introduce the main idea of a passage and provide a roadmap for the rest of the text. For example, the opening paragraph of a passage might state, "The purpose of this paper is to explore the relationship between social media and mental health." This statement clearly indicates the main idea of the passage.
Topic sentences are sentences that express the main idea of a paragraph. They are usually located at the beginning of a paragraph, but can also be found at the end. For example, a topic sentence might state, "Social media can have both positive and negative effects on mental health." This sentence expresses the main idea of the paragraph that follows it.
Signal words and phrases are words or phrases that indicate the relationship between ideas. They can help you identify the main idea of a passage by showing how the different parts of the passage are connected. For example, signal words and phrases such as "in conclusion," "in summary," or "in essence" often indicate that the following sentence or paragraph will state the main idea of the passage.
By paying attention to titles, subtitles, opening paragraphs, topic sentences, and signal words and phrases, you can gain a clear understanding of the main idea of a long passage.