Read the frame first: main ideas before details
7 min
Academic exam passages are engineered: the first paragraph introduces a topic and usually ends by signaling the passage's direction; each body paragraph opens with a sentence stating its job; the details exist to support that sentence. Skimming is not reading fast — it is reading only the frame: the full first paragraph, the first sentence of each body paragraph, and the final two sentences. This takes about 90 seconds and answers three questions: What is the topic? What does each paragraph do? Where is everything located? You are building the map you will navigate with while answering questions.
Worked example
First sentences of a five-paragraph passage: (1) "Cities are consistently warmer than the rural areas that surround them…" (2) "The most important cause is the replacement of vegetation with paved surfaces." (3) "The geometry of cities intensifies the effect." (4) "The consequences are not evenly shared." (5) "Cities are experimenting with remedies."
From five sentences you already know the passage's architecture: definition → cause 1 → cause 2 → consequences → solutions. Now suppose a question asks why the effect is strongest at night. "Strongest at night" is about how the effect works — so it must live in paragraph 2 or 3, the cause paragraphs. You go directly there instead of re-reading everything. That location step is the entire payoff of skimming.