1. The Topic: This is the main subject of the paragraph. It tells the reader what the paragraph will be about.
2. The Controlling Idea: This is the specific point or argument that the paragraph will make about the topic. It provides a focus and direction for the paragraph.
Example:
Topic Sentence: _The use of social media has had a significant impact on modern communication._
* Topic: The use of social media
* Controlling Idea: has had a significant impact on modern communication
Note: Not all topic sentences explicitly state both parts. Sometimes the controlling idea might be implied, especially in shorter or less formal writing. However, the two elements are always present in a well-constructed topic sentence.