Signals: Headings, Topic Sentences, and Transitions

Use text signals to locate main ideas quickly and understand how a text is organized.

Authors leave signals that point toward main ideas. Headings name the focus of each section. Topic sentences, often at the start of a paragraph, state that paragraph's main idea. Transitions show how ideas connect: 'for example' introduces support, 'however' introduces contrast, 'as a result' shows effect, 'most importantly' flags priority. Read this original paragraph: 'Coral reefs are under threat from rising ocean temperatures.

When water gets too warm, corals expel the algae living in them and turn white, a process called bleaching. As a result, the corals lose a major food source. However, some reefs have recovered when temperatures returned to normal. ' The topic sentence states the main idea: reefs are threatened by warming. 'As a result' marks an effect. 'However' adds a complicating, hopeful point. Be aware that topic sentences aren't always first; sometimes they come last, as a conclusion.

And some paragraphs have no topic sentence at all, so the main idea must be inferred.

• 1Headings name a section's focus
• 2Topic sentences often state a paragraph's main idea
• 3Transitions show relationships between ideas
• 4Topic sentences can come last or be missing