Teaching main idea covers a lot of subjects. It can include teaching theme, determining importance and even the author's message or the main lesson from the text.
The critical thing to remember is this: The concept of main idea differs between fiction and nonfiction texts.
Teaching main idea by genre
In fiction texts, the main idea is much more heavily weighted toward the author's message. An example would be, “Never give up on your dreams” from the story of Cinderella.
In nonfiction texts, the main idea is what holds the facts together. Although, as you'll see below, there's still room for an author's message in nonfiction texts.
The impact of this distinction is that it's important to teach determining importance separately for fiction vs. nonfiction books.
Starting with fiction
I believe it's best to start teaching theme (main idea) with fiction books. Kids simply “get” the point of a story easier than they understand the point of a nonfiction selection. But there are dangers here if you don't take into account the typical approach children will use to explain their thinking.
And this is where we learn the importance of the word “because.”
In the Cinderella example given above, a student should be saying that the main idea is “Never give up on your dreams because…” followed by supporting details from the text.
Details, details, details
If we don't insist upon the supporting elements from the text, children will naturally fall back on their generalized thoughts and opinions, such as “because it's important to always to pursue something you want to do.”
When they must draw examples from the text, it forces them to read much more carefully and think more deeply about the story.
Author's message as a main idea
As I mentioned above, in fiction, the author often has a purpose or a motive for writing the story, and that is the main idea that we are striving to pull out.
But consider this: at the elementary level, in my estimation, approximately 50% of the themes presented in storybooks are “believe in yourself,” and the other 50% are “accept others.”
I'm exaggerating a bit… but not much!
These are very important themes, but to get the main idea, children must answer the questions:
“How do you know that?”
“What did the author tell you about that?”
Without this depth of probing, the children will not get the point of teaching theme in the fiction world.
The tendency of most children when asked to explain the theme of a nonfiction text is to simply restate the title, which often briefly explains the contents of the book. It’s our job as teachers to ensure that our students think much more deeply than a simple restatement.
Let's look at an example.
A common text we read in my classroom is “The Five Geographic Regions of Washington State.”
It's quite tempting for a child to simply say, “There, that title…that’s the main idea,” and they would be correct on the surface. But, again, to ensure full comprehension they must follow that phrase with something like:
“…because in the text it said that the coast has higher rainfall, the center part is mountainous, etc.”
More nonfiction considerations
Don’t think that authors aren't also trying to make a point in nonfiction texts. They are, and it can be more difficult to get children to the depth of thinking necessary to understand the author’s purpose.
An example would be a nonfiction text about the importance of recycling. The author certainly has a point in the story, and that is that children should get more involved in recycling and encourage others to do so.
Putting the BITS together
Considering all aspects of determining importance, it is critical that children include “BITS” in their answers. Although it is not a perfect acronym, it stands for “because in the text it said.”
I sometimes write it up on the board to remind them and I will constantly say, “Give me some BITS.”
Extracting evidence from the text is critical in teaching main idea. For students to be successful on standardized testing, they must be able to understand the purpose of what they are reading. As long as you key in on the important use of “because…,” they'll be headed in the right direction.