The main idea of a text is the argument the author is making about a particular topic. Every sentence in a passage should support or address the main idea in some way.
To identify the main idea, first identify the topic, or the subject matter of a passage. The main idea is what the author wants to say about that topic.
Consider a political election. A candidate is running for office and plans to deliver a speech asserting her position on tax reform, which is that taxes should be lowered. She will support her position by explaining how lowering taxes will benefit the public. The topic of the speech is tax reform, and the main idea is that taxes should be lowered.
Other candidates may have different perspectives on the same topic. They may think higher taxes are necessary or current taxes are adequate. Their speeches, while on the same topic (tax reform), would probably have different main ideas supported by different examples and evidence.
The topic, and sometimes the main idea of a paragraph, is introduced in the topic sentence. The topic sentence usually appears early in a passage.
To determine the topic, ask yourself what you’re reading about. To determine the main idea, ask yourself how the author feels about that topic.
There may also be a summary sentence at the end of a passage. As its name suggests, this sentence sums up the passage, often by restating the main idea and the author’s key evidence supporting it.
Understanding the main idea can help you summarize a passage. A summary is a very brief restatement of the most important parts of an argument or text. To build a summary, start by identifying the main idea, then add the most important details that support that main idea. A good summary will address ALL the ideas contained in the passage, not just one or two specific details.
The summary sentence of a paragraph frequently (but not always!) comes at the end of a paragraph or passage, because it wraps up all of the ideas the passage presents. This sentence gives the reader an understanding of what the author wants to say about the topic and what conclusions can be drawn about it.
An author makes their argument using supporting details, which make up most of a text passage. Supporting details can include facts and opinions. Facts are based in truth and can usually be proven. They are pieces of information that have been confirmed or validated.
An opinion is a judgment, belief, or viewpoint that is not based on evidence. Opinions are often stated in descriptive, subjective language that is difficult to define or prove. While opinions can be included in informative texts, they are often of little impact unless they are supported by some kind of evidence.
Readers should be able to differentiate between facts and opinions to more effectively analyze supporting details.
Supporting details are often introduced by signal words that explain to the reader how one sentence or idea is connected to another and hint at supporting ideas. Signal words can indicate new information, counterarguments, or conclusions.