What is a main idea? | Reading | Khan Academy

- [David] 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.

- [Squirrel] Say, what's the big idea?

- [David] Yes, exactly.

Wait, what?

Oh, hello squirrel.

- [Squirrel] You heard me, big legs.

What's the big idea?

Were you tromping all
over my patch of forest

without so much as a how do you do?

- [David] I'm sorry.

How do you do?
- Hello.

- [David] How can I make it up to you?

- [Squirrel] Well, okay.

I'm working on a school assignment.

- [David] Squirrels have school?

- Yeah.
- All right, all right.

Sorry, go on.

- [Squirrel] 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?

- [David] Okay, a summary is all of

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?

- [Squirrel] It's about
the creek in the forest,

and how everyone wants to drink from it,

but the otters wanna swim in
it, the bears wanna fish in it,

and the beavers wanna build a dam in it

and turn the whole thing into a pond.

- [David] Not as peaceful of a forest

as I thought, huh?

- [Squirrel] Not so much, no.

- [David] 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.

- [Squirrel] So you just zipped
all the supporting details

out of my summary, and made
it more about the ideas?

- [David] Yeah, exactly.

The main idea is that different
animals wanna use the creek.

- [Squirrel] Can you give me
a more complicated example?

- [David] 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 gonna make notes,

and then I'm gonna
summarize each paragraph.

And then, I'll take all those summaries,

put 'em 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 20%

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 gonna 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,
can strengthen your brain.

- [Squirrel] So how should I
be thinking about main ideas?

- [David] All right.

So, are you familiar with the expression,

"You can't see the forest for the trees"?

- [Squirrel] David, I live in a forest.

Of course I'm familiar.

- [David] 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.

- [David] 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 is a forest.

All of those things together

add up to the idea of a forest.

- [Squirrel] But do they add up

to you doing my homework assignment?

- [David] They do not.

- [Squirrel] Aw, nuts.

- [David] You can learn anything.

David, out.