Main idea and support
The idea
A main idea expresses what a passage primarily explains or argues. Supporting details develop it through facts, examples, or reasons. A topic is usually a word or phrase, while a main idea is a complete statement. Avoid choosing a vivid detail that covers only part of the passage.
Worked example
A passage describes library reading clubs, research help, and computer access. “Libraries provide several kinds of community learning support” covers these details better than “Libraries have computers.”
Another application
If a text discusses eruption types, monitoring, and risk planning, a statement about monitoring alone is too narrow. A broader main idea might connect several ways people study and respond to volcanic activity.
A common misunderstanding
The first sentence is not always the main idea. Check whether a proposed statement accounts for the passage as a whole.
Try it yourself
Read a short informational text. Write its topic, a one-sentence main idea, and three details that support that statement.
Check your understanding
Is “volcanoes” a complete main-idea statement?
Reveal the explained answer
No. It is a topic; a main idea states something about volcanoes.