Academic passages: main idea and purpose
Academic passages: identify the main idea, the purpose of paragraphs and the author’s overall aim.
In this lesson you will
- Identify the main idea of a passage
- Explain why the author mentions something
- Distinguish main ideas from supporting details
Learn
Main idea questions: What is the passage mainly about? The answer covers the whole passage — not one paragraph or detail. Wrong options are often too narrow or too broad.
Purpose questions: Why does the author mention X? — usually to give an example, support a claim, contrast, or introduce a problem. Look at the sentence before X.
Paragraph roles: introduce topic → explain → example → counter-evidence → conclusion. Mapping them in 3–4 words helps.
Read efficiently: first and last sentences of paragraphs carry most structure; details can be scanned later.
Examples
- Too narrow: “The diet of one bird species” (when the passage is about bird migration).
- Why does the author mention the Arctic tern? → as an example of a very long migration.
- Paragraph map: P1 question; P2 old theory; P3 new evidence; P4 implications.
Vocabulary
main idea
the central point of the whole text
supporting detail
information that backs up the main idea
too narrow
covering only part of the text
too broad
wider than the text
illustrate
give an example
In real life
Read the passage.
For centuries, people wondered how migrating birds found their way across thousands of kilometres. Early naturalists suggested that birds simply followed coastlines and rivers, but this could not explain journeys across open ocean.
Experiments in the twentieth century revealed several tools. Some species use the position of the sun, adjusting for its movement during the day. Others navigate by the stars; young birds raised under an artificial planetarium sky oriented themselves by the star patterns they were shown.
More recently, researchers have found evidence that many birds can sense the Earth’s magnetic field. Proteins in their eyes may allow them to ‘see’ magnetic direction. Most scientists now believe birds combine several of these methods rather than relying on only one.
Practice
What is the passage mainly about?
Lesson quiz
A main idea answer should cover…
Review
Key points
- Main idea covers the whole text.
- Purpose: example, support, contrast, problem.
- Map paragraph roles.
- Avoid too narrow/too broad.
What you learned
- ✓ I identify main ideas.
- ✓ I explain author purpose.
- ✓ I map paragraphs.