Here is an animated PowerPoint lesson on main idea. The slideshow explains main idea and how to identify it in a text. There is also a practice activity at the end of the lesson with five practice problems.
R.2 - Determine central ideas or themes of a text and analyze their development; summarize the key supporting details and ideas.
RL/RI.K.2 - With prompting and support, identify the main topic and retell key details of a text. RL/RI.1.2 - Identify the main topic and retell key details of a text. RL/RI.2.2 - Identify the main topic of a multiparagraph text as well as the focus of specific paragraphs within the text. RL/RI.3.2 - Determine the main idea of a text; recount the key details and explain how they support the main idea. RL/RI.4.2 - Determine the main idea of a text and explain how it is supported by key details; summarize the text. RL/RI.5.2 - Determine two or more main ideas of a text and explain how they are supported by key details; summarize the text. RL/RI.6.2 - Analyze how a particular sentence, paragraph, chapter, or section fits into the overall structure of a text and contributes to the development of the ideas. RL/RI.7.2 - Analyze the structure an author uses to organize a text, including how the major sections contribute to the whole and to the development of the ideas. RL/RI.8.2 - Analyze in detail the structure of a specific paragraph in a text, including the role of particular sentences in developing and refining a key concept. RL/RI.9-10.2 - Analyze in detail how an author’s ideas or claims are developed and refined by particular sentences, paragraphs, or larger portions of a text (e.g., a section or chapter). RL/RI.11-12.2 - Analyze and evaluate the effectiveness of the structure an author uses in his or her exposition or argument, including whether the structure makes points clear, convincing, and engaging.