CHANGE Project

Climate Change Narrative Game Education

Teacher Notes: Chemistry Unit – Properties of Water

Lesson Time: 37 minutes (13 minutes available for classroom administration)

Instructor Note: These notes include a “sample lesson” that is intended to provide an example

of how this information could be presented to a classroom. The sample lesson is written in a

conversational tone and often does not follow the normal rules of writing (we don’t talk the way

we write). If you are very familiar with the topic, then the CHANGE team recommends that you

quickly skim through the material to make sure there are no surprises or changes. If you

relatively new to this material, then a more careful reading is in order.

Each section of the lesson includes the anticipated time that you will spend on each

subject (to the nearest minute, rounded up). The time estimates are intended as a tool to help you

manage the classroom, and are not a hard and fast rule. If your students are asking very fruitful

questions in a section that wasn’t allotted enough time, allow the questions (within reason). You

can make this time up by asking fewer questions later or by abbreviating topics that were

partially covered by the earlier questions.

Sample Lesson

Overview: (est. time: 1 min)

Today we’re going to talk about properties of water.

Water is a very special substance that we take for granted,

and I’m willing to bet that you’re about to learn some new

things about this stuff that you see, use and drink every

day.

Fundamental States of Water: (est. time: 2 min)

There are many, many states of matter, with more being

discovered all the time. But, there are four fundamental

states of matter that we experience in ordinary life.

Everyone knows what solids, liquids and gases are, but

some of you might not be that familiar with plasma. Conceptually, plasma is pretty easy to

understand. Whenever the conditions are right, some of the electrons from an atom stop orbiting

the nucleus and start doing their own thing, and this is what we call plasma. In nature, we find

plasmas in places where it is ridiculously hot, like at the Sun, which is a big ball of plasma and

makes up 99.8% of our solar system. We can also make plasmas by running extremely high

voltages through gases, which is how neon signs and those energy efficient fluorescent lights

work. Because of the high energy states required to make a plasma, compounds tend to break

down into elemental molecules and atoms. So, even though there’s plenty of hydrogen and

oxygen in the Sun, there’s no water.

On the surface of the Earth, we have lots of water in its solid, liquid and gaseous states.

And, almost all of the water you can find on Earth is liquid. When astronomers are looking for

Earth-like planets, they always talk about the Goldilocks zone, where a planet would be the right

sort of temperature to have water in all three of its states. On the Earth, we have liquid water,

and then just a little bit of the other two, and that works pretty well for us.

Distribution of Solid Phase of Water: (est. time: 3 min)

When we use the terms “states of matter” and

“phases of matter,” we mean the same thing, and they can

be used interchangeably. When you go on to take a

chemistry course, either here or at college, the textbook

will choose one of these terms, and your teacher might choose the other. If I say one or the

other, they mean the same thing. I’m deliberately trying to help you get used to it now, because

there are plenty of things to get stuck on in higher level science courses, but this shouldn’t be one

of them.

QUESTION: Where do you think most of the world’s ice is at?

ANTICIPATED RESPONSE: Greenland (pictured)

TEACHER FEEDBACK: You’re partially correct, it is locked away somewhere in an ice sheet.

Anyone else want to take a guess?

ANTICIPATED RESPONSE: At the North Pole?

TEACHER FEEDBACK: Although the North Pole is covered in ice, but there’s no continent

there, so it’s floating sea ice that’s only 3 or 4 meters thick.

ANTICIPATED RESPONSE: At the South Pole?

TEACHER FEEDBACK: Yes, and for everybody else what continent is that?

ANTICIAPTED RESPONSE: Antarctica

TEACHER FEEDBACK: Antarctica has been slowly building up its ice for millions of years,

and the central areas of the ice sheets in Antarctica are 3 to 4 kilometers thick.

So, let’s stop a second and think about this. The Arctic sea ice around the North Pole is

only 3 or 4 meters thick, but the Antarctic ice sheet is 3 or 4 kilometers thick. The U.S. has

permanent bases in Antarctica, but we only use satellites to collect data about the Arctic. It isn’t

because we don’t care about the Arctic, but because the Antarctic ice sheets are so thick and they

have a lot of information hidden in them. People have devoted entire careers to looking at for

their clues to discover what the conditions must have been years ago when the snow fell. The air

that was trapped in the snowflakes as they fell millions of years ago is still there, the pollen is

still there, the various isotopes and so on. In the Arctic, most of the sea ice melts every summer

and then refreezes in the winter. As a taxpayer, I want the most from every dollar I pay into our

science budget. So, if we have to train, equip, and ship people and machines, then I want to send

them where they can do the most work. Having said that, the Russians build science stations on

the drifting Arctic sea ice every year or two, but it makes sense for them because their Northern

border is right there.

Distribution of Gas Phase of Water: (est. time: 4 min)

QUESTION: Weather forecasters talk about humidity all

the time, but what do think they really mean?

ANTICIPATED RESPONSE: They’re talking about how

much of the gas phase of water is in the air.

TEACHER FEEDBACK: Yes, but humidity has a very specific meaning. If I were to say that

the air is at 80% humidity, does that mean that 80% of the air I’m breathing is actually water?

ANTICIPATED RESPONSE: No, it means that the air is holding 80% of the total amount of

water it can hold.

TEACHER FEEDBACK: That’s right. I’ve never seen a weather forecaster call for 110%

humidity. And if they say there’s 100% humidity, then that’s as close to a guarantee as you’ll

get from the forecaster that it’s raining or about to rain.

The hotter it is, the faster water evaporates and the more water vapor will stay in the air

before you start seeing it condense back into a liquid. If the Sun heats up the air over the Gulf of

Mexico, ocean water will evaporate. If that humid air blows over Florida, we can tell it’s humid

because our sweat doesn’t evaporate.

QUESTION: When that air cools off as the Sun goes down, what do you think will happen?

ANTICIPATED RESPONSE: It’ll start raining.

TEACHER FEEDBACK: That’s right, the air will never go above 100% humidity, but as the air

cools off and can’t hold as much water, it makes water droplets that we first see as clouds. As

the temperature continues to go down, the amount of water that stays in gaseous form also goes

down and those water droplets get bigger and bigger until they fall down as rain.

Forecasters are always talking about the jet stream, which blows down from the Arctic,

across the northern United States, up through northwestern Europe then back to the Arctic.

There are also the trade winds in the tropics that generally blow from East to West, and then the

Southern Hemisphere has their own jet stream that blows from West to East, just like ours. I

know you’ve all seen satellite imagery of weather and you know how a lot of times you see

clouds turning in circles. You can think of these systems similar to the way that you’d think of

eddies in water where it changes direction or where two streams meet.

QUESTION: What will happen if a wall of warm, humid air from the tropics runs into the cooler

dry that had come from the Arctic and blown across the U.S.?

ANTICIPATED RESPONSE: Rain or a storm.

TEACHER FEEDBACK: These usually result in storms with a lot of wind and rain. We see this

all the time along the coast of the Gulf of Mexico. The wind is from the difference in

temperatures and the rain because the final result is too cold to hold all the water that came up

from the tropics.

Distribution of Liquid Phase of Water: (est. time: 2 min)

You’ve all heard that three quarters of the Earth is

covered in water, but if you haven’t thought about it much,

you might not realize that almost all the water is in the

ocean. The ocean is enormous and it’s deep; about 4

kilometers deep. That’s taking into account all the beaches, ridges and deep sea trenches and

averaging them all out. That’s a mind boggling volume of water.

After the oceans, the next most significant place you’ll find water is in the salt lakes and

salty groundwater. Salt lakes are normally water that used to be connected to the ocean long ago

in Earth’s geologic history, and salty groundwater is found under dry land, where it was

absorbed into the ground from the ocean or salt lakes.

Less than one percent is something that you and I could hope to put into a glass and drink

without having to do much to it first. Even with the Great Lakes that are so big that they have

tides, fresh surface water is less than a tenth of a percent of Earth’s liquid water. We have to dig

to get to the rest of the freshwater, and ancient wells have been found, dating to over 7,000 years

ago.

Global Water Budget: (est. time: 4 min)

If we account for water the same way we account

for our money, we end up with something called a water

budget. If you go on to advanced study in ecological

systems, they’ll talk about water budgets for a specific city

or region. In the Tampa Bay area, people use pretty much the same amount of fresh water every

day which must be replaced by rivers and rainfall, or else we have a drought. In the Tampa Bay

area, if it were to rain a little more or a little less due to climate change, we’d be able to adjust

pretty easily. On the global scale, we look at the water budget by examining the different states

of water. The problem we see in the global water budget is that a lot of the world’s ice is

changing to liquid.

The graph on the left shows us how much deeper the sea level used to be compared to

today. The blue line was published geophysicists that worked for the oil giant Exxon back in the

70’s. The scientists used core samples from Exxon’s previous oil exploration, along with other

data that wasn’t released to the general public. Their purpose was to find the probable location

of ancient swamps and other places where dense plant sediments would break down over

millions of years to become oilfields. After Exxon used their data to stake as many claims as

they could, the scientists published their results.

These results were surprising to many who thought that the oceans might change by a

few meters and that was it. And here they are talking about more than 200 meters, which puts

the highest point in Florida a football field underwater. This was in the 1970’s right after the oil

crisis, so people probably trusted big oil even less. It shouldn’t be a surprise that people were

skeptical of these guys’ findings, especially since they wouldn’t publish their data. This is where

the Hallam study comes in, in the early 80’s. They weren’t being funded by a company that

stood to make billions over the research, but these scientists would certainly make a name for

themselves if they could prove Exxon wrong. They didn’t have as many data points as Exxon,

but their results agree that the ocean is usually much deeper than it is right now. Up until about

250 million years ago, their graphs pretty much agree, but then as you go farther back the errors

start to pile up, like the spike on the right.

Now, if I were a geologist that had just discovered an ancient meteor impact, and

somehow knew the exact date it happened, I wouldn’t use either one of these graphs to decide if

the meteor had hit on land or in the sea. That wasn’t the intended purpose of either one of these

graphs. They were looking for general trends and every data point represents at least a million

years, and today we now that sea levels can change noticeably over the course of a human

lifetime. If I wanted to find out if a specific layer of the Earth was above or below sea level

when it formed, I’d rely on other evidence, such as the presence or absence of marine fossils in

and around that layer.

Global Water Budget Calculations: (est. time: 3 min)

TEACHER’S NOTE: This can be accomplished with

Algebra I level math. Most students should be able to solve

this if you give them a minute to think it through. The

solution is revealed when you advance the slide.

QUESTION: Now I need you to put your thinking caps on, and you are allowed to use a

calculator or borrow one from a friend. What happens to the ocean if, as climate change

continues, ice melts and we are only left with 0.7% of the Earth’s water locked up as ice? I’m

looking for a solution to the nearest meter, and I’m going to give time for everyone to try to get

the answer.

TEACHER’S NOTE: After a few students seem to have worked it through (~30 seconds) invite

them to help each other:

If you’re stuck, you can borrow a neighbor.

TEACHER’S NOTE: After most have worked it through (or student discussions are starting to

move away from the topic at hand), call on a specific student:

QUESTION: <Student> what did you come up with?

ANTICIPATED RESPONSE: 41 meters

TEACHER FEEDBACK: Remember we’re looking for the total ocean depth, not just the

change.

ANTICIPATED RESPONSE: 4,041 meters

ADVANCE SLIDE TO REVEAL SOLUTION

TEACHER FEEDBACK: Very nice. There are several ways to work it through. On the slide is

one way, or another way is to set it up as a system of equations with 4,000 over 98.3 is equal to

“x” over 97.3, and then solve for “x.”

QUESTION: Does everyone see how we got this?

ANTICIPATED RESPONSE: None (If this wasn’t understood, it’s worth explaining or working

it on the board. They will see something similar in their lab experiment.)

The difference between 4,000 meters and 4,041 meters deep doesn’t sound like a whole

lot, now does it? Not unless you happen to live in those 41 meters that would now be

underwater. If you do the conversion, that’s about 135 feet. Florida’s average height above sea

level is 100 feet or about 30 meters; not much of Florida would be left if this happened.

Marine Water Properties: (est. time: 2 min)

QUESTION: Why can’t humans drink marine water?

ANTICIPATED RESPONSE: Because of all the salt in it.

TEACHER FEEDBACK: Exactly, all that salt messes with

our biochemistry.

Aside from its effects on us, all the salt dissolved in the water changes its properties, too.

Seawater has a lot of different minerals dissolved in it, but if you were to separate them out,

you’d have a whole lot of sodium chloride, which is regular table salt and then, relatively

speaking, not much else.

QUESTION: Why is salt water denser than pure water?

ANTICIPATED RESPONSE: Because of all the salt dissolved in it

TEACHER FEEDBACK: What is it about the salt that makes the water denser, though?

ANTICIPATED RESPONSE: Is the salt denser?

TEACHER FEEDBACK: Salt is much denser than water. In salt mines, they are literally

digging up truckloads of salt rocks that formed as ancient salt lakes and parts of the ocean dried

up.

Marine Water Properties: (est. time: 3 min)

In elementary school, your science teacher probably

told you that water freezes at 32 degrees Fahrenheit or 0

Celsius and boils at 212 Fahrenheit or 100 Celsius. Like

all things, it’s really not that simple. Anyone that has

baked a cake by following the instructions on the box knows that they give different times and

temperatures, depending on the altitude. The boiling point of water at the mile high stadium in

Denver is actually 203 Fahrenheit or 95 Celsius. That’s still hot, but that isn’t a trivial

difference.

Similarly, when you dissolve things in water, the freezing point tends to drop and the

boiling point tends to rise. That’s why you don’t have pure water in your car’s radiator, because

it would just boil away. That’s also why they put salt on the roads up North during the winter. It

lowers the water’s freezing point, so the snow and ice doesn’t build up on the road.

In marine water, the impurities are mostly sodium chloride; regular table salt. There is a

little bit of magnesium, sulfates and other stuff in there, but just enough so that you can taste the

difference. The sea salt you find at the grocery store is just what you think it is: the stuff that’s

left when you evaporate sea water. Enough people like its slightly different taste to keep it on

the shelves, but from a dietary perspective, there isn’t much difference (source:

http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/sea-

salt/faq-20058512).

That salt dissolved in marine water acts just like salt on the roads up North. The freezing

point of the ocean is a few degrees below 0 Celsius. Here in Florida, that really isn’t much of a

concern, but you don’t have to go too far up the East coast for it to start to matter. In the Arctic,

the average temperature in the summer is around 0 degrees Celsius, which, because of the salt, is

warm enough to keep it from completely freezing into a thick sheet of ice like in Antarctica.

Thermal Expansion of Water: (est. time: 3 min)

We’ve been talking for a little while about how

most of the science you were taught in elementary school

was just an approximation. Next up is how the volume of a

given mass of water isn’t constant. Water expands as you

heat it, and to help put this in context, if you’ve had to work on a car, you know that the caps and

bolts are easier to take off when the engine is warm. That’s because the metal expands and the

fittings aren’t as tight when they’re warm. In the same way, this also happens with water.

When you take the temperature of something, you are really measuring the average

kinetic energy of its molecules. When we talk about kinetic energy, we’re talking about the

energy that something has based on its motion. In any substance, the molecules are moving

around in random directions extremely fast, but they can only move a little bit before they hit

another molecule and bounce off in a new random direction. The combined motion of all the

molecules is usually zero, unless you are talking about a moving object. As water heats up, the

molecules start crashing into each other more and more violently, and these collisions start to

overpower the inter-molecular attractive forces that hold them together. At the macroscopic

level, we see this as the water expanding. Ultimately, there will be a temperature where the

inter-molecular forces are totally overcome, and we call this the boiling point. In general, water

doesn’t exist as a stable liquid above its boiling point.

The graph here shows the specific volume of water versus its temperature. “Specific

volume” is a shorter way of saying how much room a kilogram of something takes up. Water, at

its densest point, used to be the way we defined the liter, and a liter is, in turn, defined as 1/1000

of a cubic meter. So there should be no surprise that water, at its densest, is exactly 1 liter per

kilogram. As the temperature increases, though, so does

the volume. By the time water reaches its boiling point, it

has increased in size by about four and a half percent.

You’re actually going to try to prove this as a lab

experiment tomorrow, and we’ll see if you come up with

the same conclusions as the scientists.

Thermal Expansion of Water Calculations:

(est. time: 2 min)

TEACHER’S NOTE: This is a straightforward calculation because of the assumptions. The

results they get will be very close to actual results if the varying temperatures/rates at various

depths are accounted for. This problem can be solved more accurately using Calculus, but

conceptually there is little difference using this approximation.

Okay, it’s time to do some math again. You’re going to calculate the effect of warming

oceans has on the sea levels. Because of various effects, only the top 1,000 meters or so feel a

significant warming due to global climate change. In the previous slide, you saw that the

expansion rate wasn’t a straight line, but instead it increased as the temperature increased. Here,

we’re going to take the average expansion rate as 1 percent for every 20 degree Celsius, which

works out to 0.05 percent per degree.

QUESTION: What will the depth of the ocean be if its temperature raises by a degree? This

should be a simpler calculation than last time, and I expect everyone to give it a go. Again, if

you get stuck, ask a neighbor.

TEACHER’S NOTE: Some students will already have the answers before you have even finished

the question. The stronger students should be able to explain the math to others that are

struggling within 30 seconds.

ANTICIPATED RESPONSE: Half a meter

TEACHER FEEDBACK: Is that what everyone else got?

ANTICIPATED RESPONSE: (general agreement; no negative responses)

ADVANCE SLIDE TO REVEAL SOLUTION

TEACHER FEEDBACK: In case anyone is still having trouble, this was how we solved it.

The water just rises by a half meter. The coastline in the Tampa Bay region would be

devastated, and Miami and most of the tip of Florida would be completely underwater.

Climate versus Weather: (est. time: 1 min)

We’ve talked about the difference between climate and

weather before, but there’s a couple things I want you to

consider.

QUESTION: Because we have pretty good evidence that

global climate change is happening, what do you think is happening to the temperature of the

ocean?

ANTICIPATED RESPONSE: It’s warming up.

TEACHER FEEDBACK: In general you’re right, but just like climate change doesn’t always

mean warming of the atmosphere, it also doesn’t always mean warming of the ocean. We’ve had

satellites measuring ocean surface temperatures across the globe since the 1970’s and most

waters are warming, but in some places it’s actually cooling.

Choices and Human Impact: (est. time: 6 min)

QUESTION: By a show of hands, how many of you think

that climate change is just going to happen and there’s

nothing you can do to change it? And be honest.

ANTICIPATED RESPONSE: Many, if not most hands will

raise

TEACHER FEEDBACK: During your parents’ generation, scientists discovered that we were

destroying the ozone layer which protects us from getting fried by UV radiation from the Sun.

The culprit was a class of chemicals called CFC’s that were used as the refrigerant in just about

every air conditioner on the planet. It took about a decade for enough people to understand the

problem, but then every modern country mutually agreed to stop using CFC’s, even though that

meant things might cost a little more. Today, worrying about ozone depletion is a thing of the

past, and the ozone hole your parents thought was going to be the end of the world is almost

gone.

It will only be a couple years before you guys can vote and you will have enormous

influence on our national policies. But, even now the choices you make matter. When you buy a

car, you might be concerned about fuel economy because you don’t want a car with a tank you

can’t afford to fill up. Let’s suppose you are independently wealthy, or want to pretend that you

are. Does fuel economy still matter? I’m not going to ask what kind of car you or your parents

drive, but when you are in the market for a new one, maybe this is something you should think

about.

The first time we really talked about climate change, I said that electric power plants are

the leading source of greenhouse gases. TECO uses coal at its largest power plant in Apollo

Beach, and coal is the worst thing you could use, at least from a climate change perspective.

QUESTION: Why do you think they don’t just build something else that’s more efficient?

ANTICIPATED RESPONSE: Money

TEACHER FEEDBACK: There are some up-front costs, but nuclear, wind, and solar are all

cheaper over the long run. Anyone else have an idea?

ANTICIPATED RESPONSE: They’re short sighted.

FOLLOWUP QUESTION: Has anyone heard of something called the NIMBY Syndrome?

ANTICIAPTED RESPONE: (no reponse)

TEACHER FEEDBACK: NIMBY is an acronym that stands for Not In My Back Yard. The

power plant in Apollo Beach was built in 1970, and then in the late 90’s really high-end

waterfront homes were built within a half mile of it. They’re about as close as you can get and

still be able to mostly hide the plant behind the trees. Anybody think that power station would

have a chance of getting built there today? Probably not. Does anybody think that rich people

are the only ones that would get angry if you told them you were going to build a power plant

next to them?

QUESTION: So the question is, where do we build the newer, better power station that

everyone knows we need?

ANTICIPATED RESPONSE: There are lots of open areas near (some wildlife

preserve/swamp/marsh area).

TEACHER FEEDBACK: Anytime you want to build a major utility, it has to get local approval.

The answer is always, “We want the services, but you have to build it somewhere else. I want

the services, but I don’t want it in my backyard.” I’m not saying they’re completely blameless,

but TECO probably should get a pass on this issue. I’m certain they would build a modern

power station if people would just let them.

At the same time, we make choices every day that have a minor impact on our

environment. Individually, these choices might seem trivial, but they add up pretty quickly.

QUESTION: If you had a friend that said, “I’m only one person, and what I do doesn’t really

matter in the grand scheme of things,” what might you say to them.

ANTICIPATED RESPONSE: I’d tell them that if everyone thought that way, things would get

much worse.

TEACHER FEEDBACK: That’s good, anyone else?

ANTICIPATED RESPONSE: You can tell them that we all have to do our fair share or else

we’re putting everyone’s future in jeopardy.

TEACHER FEEDBACK: You’re absolutely right, but that also implies that you have to trust

that most people will do the right thing in order for things to get better. We’ve seen that in the

past, so there’s no reason that it won’t happen in the future.

Summary: (est. time: 1 min)

We covered a lot of material today. Does anyone have any

questions about water? I bet nobody ever thought they’d

get asked that. But, seriously, we did go through a lot of

stuff today, and you’ll see some of this again when we do

the lab. So if you have any question, now would be a good time to ask.