Central, most important idea in a paragraph or whole text
Strategy: 1. Look at the title, 2. scan for subheadings, bold text and pictures, 3. find out who or what each paragraph is about, 4. decide the most important thing that is said about the who/what.
Main idea can be one of the sentences in a paragraph or words found accross several sentences (then you have to write your own main idea)
NOT ALWAYS but often first or last sentence of a paragraph