A few years ago, I was conducting writing trainings for teachers. In those trainings, I would ask, "How do you teach your students main idea?" Sooooo many teachers would say, "I tell them to look for the sentence that the article or story is mostly about." Then with a slanted smile I say, "Ok, I'm going to show you this primary article and you write down the sentence that has the main idea on your post-it" I showed a primary nonfiction article from Ranger Rick's Your Big Back Yard and guess what... the main idea is not there... point taken. At this juncture, I have to retrain teachers to not lead their students down the path of hunting and searching for the main idea but rather to generate main ideas on their own by using what the author DOES include in the article which are the details.
Here's an equation I use in my class:
Main Idea = Topic + what the author is telling about the topic
Also, I had all of the teachers close their eyes and I say, "OK, I'm going to give you a main idea and I want you to picture it in your head. My mom takes me to the best places." Once everyone opens their eyes, we share what they pictured: the beach, the mall, Disney World, and the list goes on. This is when I point out that a main idea CANNOT be drawn or pictured but a detail CAN! Try it with your class :)
So here is the first of my main idea/detail graphic organizer activities with the article included! Check it out at my TPT Shop!