Glossary
main idea
The main idea is the single point the whole passage was written to deliver — what everything in it adds up to, not the first sentence or the longest one.
The main idea is the one point the passage was written to deliver. It is not always a single sentence — a passage can imply its idea — and it is not the first sentence or the longest one: it is the claim the other sentences support, so it has to cover everything in the passage and nothing outside it. A passage about a town's new bus shelters has its main idea in what the town decided and why, not in the survey that led to the decision or the price of the materials — those are details doing work for the point. Two question shapes ask for it: a statement question (what is the passage mainly about) and a title question (which title best fits). Both are answered the same way — say the point in your own words first, then find the option that matches. A distractor that states a true detail is a common wrong answer, because it is the one that feels like the passage.
Taught in
Source: The reading skills ATI names in its own Content Outline (R.1.1-R.1.6, under the Key ideas and details sub-content area); each definition below is written for the Key Ideas and Details guide in this exam, in our own words, and explains the skill the way the guide teaches it. (ATI Content Outline read 2026-10-08; definitions written 2026-10-09)