Determine the main idea of a passage
key notes:
Main Idea:
- The central or most important point the author wants to communicate.
- It answers the question: What is the passage mostly about?
Topic Sentence:
- Often found at the beginning or end of a paragraph.
- It introduces or summarizes the main idea.
Supporting Details:
- These are facts, examples, or explanations that clarify and provide more information about the main idea.
- They answer the how, why, or what about the main idea.
Steps to Identify the Main Idea:
- Read the passage carefully.
- Ask, What is the author trying to tell me?
- Look for repeated ideas or themes.
- Find the topic sentence if it’s clear.
Summarizing:
- Condense the passage into 1-2 sentences that capture the main point.
Let’s practice!
Read the passage.
AC vs DC
In the 1880s, the War of the Currents began. Thomas Edison developed direct current, or DC, a type of electricity that flows in one direction. By 1887, DC was in use around the United States. It had some drawbacks, though. Converting it to lower or higher voltages was difficult; that is, the current’s force couldn’t be changed easily. Transmitted at the low voltage needed for use in homes and businesses, it lost power after travelling only one and a half kilometres. Meanwhile, Nikola Tesla was working with alternating current, or AC. AC reverses direction many times per second and can be changed to different voltages. At high voltage, it can be transmitted efficiently, travelling hundreds of kilometres with little energy loss. Because of its advantages, AC triumphed by the end of the nineteenth century.