So look at this.

God, that's amazing.

Oh, and it doesn't take much of a squeeze at all.

You are now compressing some of the air

that's in that packet.

So I bet you think this is the part of the show where I'm

going to say, don't try these experiments at home.

And you're right, except there is one experiment

we want you to try.

Just look for the graphic that's right here

that says try it.

That's your signal that you can try that

experiment at home.

Everything else off limits.

Look, I've already given you homework, and the show hasn't

even started.

I'm Steve Spangler, and I'm all about making science fun.

For the last 20 years, I've been teaching ways to turn

ordinary science experiments into unforgettable learning

experiences.

I have an amazing team who will do whatever it takes to

affect the way people think about science.

And to do that, I live by one motto--

"Make it big, do it right, give

it class." All right.

Watch this.

There's a squid in the bottle--

seriously.

And you just take a hair like this-- it's a trained squid--

and you wrap the hair around the squid.

It's almost like a lasso.

Hard to see.

See I can kind of pull the little--

here let him go.

Just grab the hair, pull him down like this.

And you can take him to the bottom and just pull the hair

off, and he'll go right back up to the top, and--

OK, that's not how it works.

But it's the first science toy I ever invented.

And some people will ask, so how does a science teacher own

a toy company?

And the reason why is because of that dumb squid in a bottle

that goes up and down when you actually squeeze the bottle.

This is it.

It's the very, very first toy that started the toy company.

And it's nothing more than an eye dropper and a hex nut and

this little rubber piece that's the squid.

And let me show you how easy it is to make the diver.

Well, here are the pieces, parts that we're using today.

I've got just some 1 liter bottles filled with water, a

couple of deep containers, because we're going to need to

do some things that sink and float.

The original Cartesian diver, named after

Rene Descartes, used--

well, the original one, I'm sure used something other than

glass eye droppers.

The oldest one I can remember used a glass eye dropper.

And today, you can still find them at stores like Walmart or

wherever, a pharmacy.

Let me show you how to do it with the original one.

The whole idea is this.

You have to get a container of water like this here, and you

drop the eye dropper inside.

And you say float or sink, and, of course, it floats.

And it floats because there's air inside that eye dropper.

Even though it's a glass eye dropper, there's air.

If I hold it up like this-- here, take a look at this--

I can squeeze some of the bubbles out like this, and

pull some water in.

So in essence, I'm changing the mass, right?

And now it just barely bobs there.

See how it bobs up and down that way?

OK, so that's perfect.

When you make a Cartesian diver, you've got to have that

kind of set up there, so it just barely bounces around.

Now we've got a 1 liter bottle.

And I'm using a 1 liter.

You could use a 2 liter.

It's just easier to squeeze with a 1 liter.

Remove the label.

It's almost full to the top.

And one of the secrets of a Cartesian diver, to make it

easier to squeeze, anyway, is to make sure there's just no

air inside the bottle.

The only air that we want--

if you take a look at this right here-- the only air that

you want is the air that's in that Cartesian diver.

All right.

So now, here's what happens.

You take a cap and put the cap on like this.

And now, we're ready to go.

So the way it floats and it sinks is if I can change the

mass, ultimately changing the density-- if I can change the

mass, because the volume is going to stay the same, then

density equals mass divided by volume.

I know it's nerd fest here, but I've just got to change

the density so it's greater than 1 and so it will sink.

So watch-- as I squeeze it, you can actually see the water

level going up.

You see this here?

So I'm just barely squeezing it.

So water's being pushed up into here.

The air compresses, because the water cannot compress.

And when it gets heavy enough, it finally sinks.

Isn't that nice?

And as you let go, it will float.

So we've got a perfect way to be able to make something

float or sink.

And of course, we're just using our fingers to be able

to squeeze it.

You can do all the magic that you want to.

You pretend like you have the magnetic finger.

And when the person comes up, their finger follows.

And if you just don't want the person to have the magnetic

finger, then you just don't let them make it work, right?

But that's the classic Cartesian diver.

I was introduced to a new style of Cartesian diver by a

man by the name of Bob Becker.

Bob is a chemistry teacher in Kirkwood, Missouri, and

actually showed me this version using plastic eye

droppers called pipettes.

And they're very, very prevalent in

the chemistry classroom.

A lot of teachers use these pipettes.

They may be a little bit harder for just the average

person to get their hands on, but just befriend a teacher,

and for sure they know about pipettes.

This one is special, because it's graduated.

Do you see this one here?

And when you're picking one, just make sure that you can

find one that the hex nut will go over the top.

So if I drop this into the water like this-- so here's

our container.

Let me drop this into the water.

Of course it floats, right?

I want to weight it down.

So here's what we're going to do.

We're taking a regular quarter-inch hex nut.

And I use these brass ones, because they don't rust.

This goes on the pipette like that.

So here's what it looks like.

It's just right there on the pipette.

And then I'm going to twist and turn it into place like

this, so it kind of holds it into place.

And that's what it looks like.

It's held into place.

A pair of scissors will help us cut the end off.

And now we have the makings of a modern-day Cartesian diver.

So the same thing-- of course it floats.

So watch.

When we drop it inside, it floats.

If I squeeze some of the air out and pull some of the water

in, I can make it so it just barely floats.

Of course, of we have too much water in altogether, then the

whole thing will sink.

So I want it so it just barely floats.

So I'm going to just continue to play with it.

That seems to be a pretty good buoyancy there.

Again, that whole idea is so it just barely floats.

So now that we have it adjusted, you just have to be

careful that you don't get any of the water out.

It goes down inside.

Notice how it's full almost to the very, very top.

That's exactly what we want--

no air inside the bottle.

And now we cap it off.

Again, just as it happened before, that we saw with the

glass eye dropper, when you squeeze, notice how the water

goes up inside.

This systems just works perfectly.

Bob's a genius.

And there is the making of the modern day Cartesian diver.

We had to find a way to disguise

this diver right here.

I was working in television in the early 1990s for a program

called News for Kids.

And so on the set, we had a whole bunch of kids.

And they were squeezing this.

And the director kept on commenting that she couldn't

see the diver very well inside.

So we found other ways to be able to glue things on, for

example, or use a Sharpie pen to color on them.

Again, Bob Becker had a bunch of great ideas.

But I wanted something that was just a little

bit easier to see.

So I'll show you how we changed everything.

It looks like a fishing lure.

It's not really a fishing lure that would catch a fish.

These were specially made, because the regular fishing

lure just wouldn't go over the pipette.

Remember coming back and trying to find a way to be

able to use this and put it over the pipette.

So here, watch.

This is Squiddy.

So you just open up the little opening here like this.

And then this slides over the workings of

the squid like this.

And this is the new squid.

All right, so this is in place.

Enough history.

As you squeeze, the water goes inside, the little squid falls

down, and as you let go, the squid goes up again.

And that was Squiddy.

So let's say you don't have a squid and you don't have

pipettes and hex nuts and everything else and you'd like

to do the Cartesian diver.

I'm going to show you how to do one.

This is ingenious.

It's done out of a condiment.

It's just ketchup.

So you're going to start collecting

some ketchup packets.

This is an interesting Cartesian diver.

And it's interesting because, in this style of Cartesian

diver, there was an open end.

So when you squeeze, water would go inside.

You would increase the mass, and it would sink.

But when you use something like this, these ketchup

packets have never been opened.

And so this means that the mass has to stay the same.

We would have to possibly change the volume if you want

to change the density.

So here's what you need to do.

Not all ketchup packets work.

Collect a whole bunch of different ketchup packets and

in a container of water, just drop them inside.

Some will float, and some will sink.

You're hoping that a couple will float.

And pick the ones that will float.

OK, so this is a good one here.

This one may float just a little too much.

And this one right over here, this Carl's Jr. one might do

fairly well.

So you want the two of them that just barely float.

All right?

The other ones are out of the question.

So again, here's our bottle.

Let's try that Carl's Jr. one.

Let's see if this one works fairly well.

So you're going to take the ketchup packet.

Don't open it up.

Just kind of fold it and push it down into the bottle.

And you're going to lose some water, so you're going to have