The main idea is what the whole text is talking about. It is typically a sentence.
In order to find the main idea of a text, follow these steps:
Read the text slowly and carefully. Study all text features, such as maps, tables, timelines, drawings, and photographs.
Identify the topic. This is usually just 1 or 2 words, such as "Teddy Roosevelt."
Consider what the text is saying about the topic. "Teddy Roosevelt lived a busy, vigorous life." That is typically the main idea of the text.
Make sure that your main idea is accurate. Is the ENTIRE text part of your main idea?