For whatever reason in LIFE, main idea is one of the most challenging comprehension skills for students to grasp. This activity can be completed during a guided reading session with a small group. It can also be placed into a learning center for review.
I begin my lesson with a group of blocks using only two colors. I ask students to tell what color are most of the blocks. Next, I connect this to main idea and tell the students that the main idea is what most of the sentences are about.
We analyze each sentence one at a time to determine what the sentence is about and place a block next to it. If the following sentence tells about the same thing, I place a block of the same color next to it.
This process is continued for every sentence. When a sentence is about something different, a different color block is used.
The students are then able to visualize what main idea means Then, we discuss how to create a sentence that explains what most of the sentences are about. 99.9% of all students I have worked with really understand main idea after using this method.