Using Text Features to Confirm the Main Idea

Captions, diagrams, bold words, and sidebars can point toward the main idea.

Nonfiction authors use text features to highlight important information. Bold words often name key ideas. Captions explain what a photo shows and why it matters. Diagrams show how something works. Sidebars add related information. These features can help you confirm the main idea, but they can also distract you with side facts.

Imagine a section about volcanoes with a diagram labeled 'magma chamber', 'vent', and 'lava flow', a bold term 'eruption', and a caption saying 'Pressure from gas forces magma upward. ' Together they point to the main idea: 'Volcanoes erupt when pressure pushes magma up through a vent. ' A sidebar about a famous ancient eruption is interesting, but it's not the section's main idea.

Use features that repeat the body text's point; treat sidebars and fun-fact boxes as extras.

• 1Bold words, captions, and diagrams highlight key ideas.
• 2Features that repeat the text's point confirm the main idea.
• 3Sidebars and fun-fact boxes are often extras.