What is a main idea? | Reading | Khan Academy

Hello readers! Today I'm in this peaceful forest to tell you all about the skill of figuring out the main idea of a text. Say, what's the big idea? Yes, exactly! Wait, what? Oh, hello squirrel! You heard me! Big legs, what's the big idea with you tromping all over my patch of forest without so much as how do you do?

I'm sorry, how do you do? Hello! How can I make it up to you? Well, okay, I'm working on a school assignment. Girls have school? Yeah, all right, all right. Sorry, go on!

So, I've got this newspaper article, and Mr. Badgerton says I have to draw out what the main idea is. How is that different from a summary? Okay, a summary's all the key details of an article or a story. But a main idea is bigger than details. It's what those details add up to. A main idea is the key information that the author wants you to know after you've finished reading the text.

So, for example, what's going on in your article? It's about the creek in the forest and how everyone wants to drink from it. But the otters want to swim in it, the bears want to fish in it, and the beavers want to build a dam in it and turn the whole thing into a pond. Not as peaceful of a forest as I thought, huh? Not so much.

No! What you just told me is a summary of the events of the news story, but the big idea there is that there's a conflict or fight over who has access to the creek. So you just zipped all the supporting details out of my summary and made it more about the ideas. Yeah, exactly! The main idea is that different animals want to use the creek.

Can you give me a more complicated example? I would love to! Why don't we take a look at this text about brain growth? So here's a passage about training your brain. I'm going to read it, I'm going to make notes, and then I'm going to summarize each paragraph. Then I'll take all those summaries, put them together, and that'll help us come up with a main idea.

So here we go! Your brain gets stronger when you exercise it, just like muscles get stronger when you exercise them. Training your brain isn't always easy or comfortable. In fact, your brain uses up twenty percent of the oxygen and blood in your body because it works so hard.

Okay, so your brain can get stronger but it's not easy. Here are some examples of how your brain grows when you learn new things. Learning math strengthens the parts of the brain that are linked to memory, thought, and action. Imagine that! Remember when you first learned how to add and subtract? You got faster and faster with more practice! That's because your neurons—those are brain cells—your neurons were learning how to work with each other, and then your memory improved.

But memory is useful for more than just math. I'm going to underline "more than just math." That same part of your brain helps you remember basketball plays, dance routines, and even nice memories with your friends and family. So it's not just about math. Learning and practicing things helps your brain work faster.

Learning or practicing anything? Yes, anything! Learning and practicing helps strengthen and change our brains. Your brain is changing and creating new neural pathways, which is just another way of saying brain connections, right? Neural is similar to neuron, so it's like having to do with brain cells. Your brain is changing and creating new neural pathways when you struggle to learn something new.

So struggle is important! In other words, there's a lot happening in your brain when you're learning. All learning can build new information pathways, but learning things that are challenging for you can supercharge your brain growth. In other words, the more you're challenged, the faster you learn!

So here are my paragraph summaries: your brain can get stronger but it's not easy; learning and practicing helps your brain work faster; and the more you're challenged, the faster you learn. Putting those three things together, I would say that the main idea of this passage is that learning new information can strengthen your brain.

Let's get our little thinky pinky back in there! What I did was I took something from each paragraph and found what they all had in common. There were some details, for example, about math or dance practice that are important but aren't so important that they need to be included in the main idea. All of that can just sort of be pushed into this broader idea of learning new information makes your brain stronger.

So how should I be thinking about main ideas? All right, so are you familiar with the expression "you can't see the forest for the trees"? David, I live in a forest! Of course, I'm familiar! So it means, right, don't get so hung up on details that you can't see the big picture. The trees, one by one, are all part of the forest. They make up the forest, right? You with me?

Yes! A summary of the forest is all the important details: there's a stream here, there's a birch tree here, a Douglas fir tree here, a red oak tree here, a rock there. But the main idea is this: this is a forest. All of those things together add up to the idea of a forest.

But do they add up to you doing my homework assignment? They do not. Oh nuts! You can learn anything, David! Out!