THE PLANET EARTH

Do you ever have one of those days when you lay down in the grass, feel the warm sun all around you, look up at the clouds moving past, and wonder how it all happened? The earth is in many ways a miracle. Nowhere else in the entire universe has anyone discovered a place where life can exist. Sure there are other stars like our sun, and now scientists are discovering planets that orbit those stars. But so far, no one has found water, trees, grass, and a climate quite like ours here on Earth.

The planet Earth is a rare find in the universe, and it is in our care. If we don’t take care of it, its wonder and beauty may soon be in danger. One of the growing

concerns among people who are worried about the earth is the quality of our air and water. There are many ways to discover how precious these resources are.

Why did the poor scientist experiment with baking bread?

Because he needed the dough!

Fun Facts

Much of the acid rain in North America is caused by the burning of coal to produce electricity.

The rainiest day ever recorded was in 1952 in Cilaos, Reunion Island. In a 24-hour period, 73.63 inches of rain fell.

TRY THIS ACID RAIN

QUESTION

What is acid rain?

MATERIALS

Empty glass jar Water

Phenol red (available at pool supply stores) A drinking straw

acid rain: rain that contains acids formed in the clouds. It can be dangerous to

people, animals, and crops.

PROCEDURE

1.Fill the jar about half to three-quarters full of cool water.

2.Put approximately 20 drops of the phenol red into the water until it turns light red. You can practice this and adjust the amount you add, once you get the hang of the experiment.

3.Place the straw into the water and blow so that bubbles form in the water for about 20 seconds. CAUTION: Do not drink the water!

4.Check the color of the water. It should be a lighter red than it was before.

5.Repeat your 20 seconds of blowing a few more times. Before long, the water should be clear again.

WHAT’S HAPPENING

Phenol red reacts with acids to change color. (You have already learned a little

bit about acids in an earlier chapter.) When you blew into the water, the carbon dioxide you blew out (which is not the same as the oxygen you breathe in) reacted with the tap water to form a very weak acid. The more you blew, the more the acid reacted with the phenol red and turned the water clear. Pool cleaners use phenol red to measure how acidic the water is. This tells them what kinds of chemicals to add to maintain the cleanliness of the water.

FOLLOW-UP

What does this have to do with acid rain? When we place too much carbon dioxide into the air, through burning coal, gasoline, or other fossil fuels, it can react with the water in the air (rainwater) to form an acid. When that rain falls to the ground, we get acid in our water and it can become unsafe. It pays to be careful with the gases we exhaust into the air!

hemisphere: half of the earth.

anemometer: a device that measures wind speed.

PROCEDURE

1.Glue the spool of thread to the block of wood and wedge the pencil, eraser side up, into it.

2.Stick the needle into the eraser.

3.Cut two strips out of the piece of cardboard. They should be at least 16 inches long and 2 inches wide.

4.With the scissors, cut slits in the bottom of each strip so they fit together to make a cross. Start from the middle of the strip (about 8 inches from either side) and cut upward about 1 inch.

5.Glue or staple one muffin cup to each arm of the cross, making sure that each cup points in the same direction. This will ensure that every cup will catch the wind.

6.Place the sticker on one of the cups. Make sure it is clearly visible because you will be using it to measure wind speed.

7.Place the cross onto the needle so that it rotates freely. If you find that it doesn’t rotate, use the needle to make a slightly larger hole until it spins easily.

8.Place the anemometer outdoors where it can catch the wind.

9.Over the course of several days record the wind speed at different times of day.

Fun Facts

Winds are measured on the Beaufort scale, which ranges from 0 (no wind) to 12 (hurricane speeds in excess of 75 mph).

The fastest wind recorded on the ground was 231 mph in New Hampshire in 1934.

Instructions on Measuring Wind Speed Use a stopwatch or a clock that will measure one minute. Count the number of times the cup with the sticker completes one revolution in a minute. Use that number as your wind speed. Each time you record a new measurement, compare it to the previous values.

QUESTIONS FOR THE SCIENTIST

What was the fastest speed you recorded?

What time of day was the windiest? The calmest?

Are there places at your house that are windier than others? How could you test this?

How do you suppose meteorologists measure the true wind speed?1

TRY THIS MINI VOLCANO

Facts Fun

The world’s most active region for volcanoes lies in what is called the Ring of Fire, a circular region extending around the Pacific Ocean from East Asia to the United States.

QUESTION

What does an erupting volcano look like?

volcano: any part of the earth (especially mountains) that explodes when

pressure below it gets too high.

molten: melted.

MATERIALS

Small plastic bottle Baking soda

Wide tray or baking pan Sand or dirt

½ cup vinegar

Measuring cup with a pouring lip Red food coloring

PROCEDURE:

1.Fill the bottle one-quarter to half full of baking soda and place it in the middle of the tray.

2.Pile the sand around the bottle so that you can just see the opening. At this point it should look like a small volcano.

3.Pour the vinegar into the measuring cup.

4.Place several drops of food coloring into your vinegar and quickly pour it into the bottle top.

WHAT’S HAPPENING

You’ve already seen what kind of reaction occurs when baking soda and vinegar are combined. The red coloring makes this reaction appear to produce lava. In real volcanoes, you wouldn’t find any vinegar, but you would find hot gases and liquid rocks under intense pressure. When the pressure builds up too

much, the volcano explodes, and all the hot gases and rocks that have melted under the heat finally burst forth in the form of either hot ash or molten lava.

Science Online

The U.S. Geological Services Cascade Volcano Observatory (CVO) includes links to all of the world’s known volcanoes. Visit http://vulcan.wr.usgs.gov .

Head in the Clouds

Do you ever see the shapes of people or animals when you look at the clouds? Connect the numbered dots and then the lettered dots to see what familiar shape is floating overhead in this beautiful sky. HINT: To make a better cloud picture, connect the dots with curved lines instead of straight lines.

TRY THIS LAND WARMER

From the dirt in our gardens to the liquid metal core of our planet, the earth is a place where remarkable processes happen every day without our knowledge. One of the simplest processes is the manner in which sunlight warms our planet.

QUESTION

Which gets warm faster: land or water?

Where do scientists study volcanoes?

In the lava-tory!

WHAT’S HAPPENING

Sunlight warms the land much faster than it does water. That is why your cup of dirt ended up warmer than the cup of water. This also explains why, on a hot day, a sandy beach can get extremely warm while the water in the lake remains cool.

FOLLOW-UP

When you dig in the sand on a beach, does the sand feel warm all the way down, or is it only the top level that gets hot?2 Some animals dig into the earth to find cool places to make their nests. Can you find animals that do that?

Cool Quotes

Space isn’t remote at all. It’s only an hour’s drive away if your car could go straight up.

— Sir Fred Hoyle, British mathematician and astronomer

Up or Down?

What is a good way to remember the difference between a stalactite and a stalagmite? Use words from the word list to finish the following “science saying,” and you’ll never forget which is which!

KIDS’ LAB LESSONS

QUESTION How do icicles grow?

EXPERIMENT OVERVIEW In this experiment, you’ll explore the formation of icicles by building stalactites and stalagmites — towers of rockhard minerals usually found in caves deep in the earth. Surprisingly, the process by which they form is very similar to how icicles form. You’ll be using a common drugstore product called Epsom salts and you’ll get to watch the “icicles” grow right before your very eyes.

SCIENCE CONCEPT Icicles can form only under special conditions. It must be cold enough for water to freeze, but there must also be a way for ice to melt so it drips. This is why icicles are commonly found along the edge of the roof of a house. The warmth of the house can cause snow on the roof to melt and drip to the edge of the house. As the water drips off the side, some of it freezes. Later, drops run down the frozen droplets and freeze when they reach the end. In this fashion, the icicle grows drop by drop.

In caves, stalactites and stalagmites grow in the same way. The only difference is that the water that drips doesn’t freeze. Instead, each drop of water leaves behind a tiny amount of calcite, which hardens on the end of the stalactite. Eventually, enough calcite builds up and hardens that a stalactite forms. Stalagmites are formed when some of the calcite falls to the ground and gradually builds up from the floor. After a long time, the stalactites that grow from the ceiling meet up with the stalagmites growing up from the floor until they join and a column is formed.

stalactite: a long, thin piece of hanging mineral (like rock) that forms over long periods of time, often in caves.

stalagmite: a long, thin piece of mineral that grows up from the ground over long periods of time. (It is similar to a stalactite.) column: what is formed when a stalactite meets a stalagmite and the two grow together.

MATERIALS

Large glass that you can use for mixing Water

Small spoon Box of Epsom salts (available at a local drugstore)

2 small glasses

Thick string or a piece of cloth that will absorb water easily Wax paper

Fun Facts

It can take up to 4,000 years for a stalactite to grow 1inch.

PROCEDURE

1.Fill the large glass with water and stir in the Epsom salts until you cannot dissolve any more (some of the salt remains and won’t dissolve).

2.Fill each small glass with half of the solution you have prepared and place the jars on a piece of wax paper.

3.Place an end of the string in each glass and let the middle of the string hang between the glasses.

4.Watch your stalactite and stalagmite grow over the next few days.

QUESTIONS FOR THE SCIENTIST

Which of your cones is the stalactite and which is the stalagmite?

How fast did your stalactite grow (how many inches per day)?

Did the process speed up at all during your experiment?

If you live where it’s cold enough for icicles, how do you suppose they form?

How could you prevent icicles from forming on your house?

FOLLOW-UP

Do you think this experiment will work with other substances? Try baking soda, table salt, sugar, and so on. Considering the fact that Epsom salts is found in drugstores, can you find other uses for it?3

THE SKY ABOVE US

If you have ever looked up at the sky on a clear night, you have seen more stars than you can count. It gives you some sense of how large our universe is and might even make you feel like Earth is pretty small. Looking at the sky is one of the oldest activities known to man. Just about every ancient civilization had its own myths about what the stars mean. The passing of days, months, and years has long been tracked by the rising and setting of the sun, the phases of the moon, and the changing of the seasons.

The sky is blue and sunsets are red because of the way air breaks sunlight into colors. That fact alone is pretty fascinating. But for many of us, it’s hard to imagine that air is made up of anything. You can’t see it, you can’t taste it, and you can only feel it when it moves. It makes you wonder whether air is really there like everyone says it is.

When are scientists the smartest?

During the day, because when the sun shines everything is brighter!

TRY THIS SPACE OF AIR

QUESTION

Does air take up space?

MATERIALS

Balloon (minimum 9 inches) Glass bottle with a small mouth Pot of boiling water Pot of ice water Funnel

Masking tape

Water

Science Online

These links below will take you into the world of astronomy and will help you learn more about the planets and stars:

Visit Astronomy magazine at www.astronomy.com

Visit Sky and Telescope magazine at www.skyandtelescope.com

Visit the Star Gazer home page at www.jackstargazer.com

Visit The Astronomy Café at http://itss.raytheon.com/cafe/qadir/qanda.html

PROCEDURE

1.Place the mouth of the balloon over the mouth of the bottle. It should hang limply at the side of the bottle.

2.Make sure the balloon makes a good seal around the top of the bottle and gently place the bottle into the pot of boiling water. Be careful not to stand too close to the boiling water. Observe the changes in the balloon.

3.Remove the bottle from the hot water, remove the balloon, then replace it over the mouth of the bottle. The bottle now contains very hot air.

4.Place the bottle into the pot of ice water and observe the changes in the balloon.

5.Remove the bottle from the water and let it sit at room temperature for 10 minutes.

6.Remove the balloon from the top of the bottle.

Can you think of other examples of air expanding or contracting that you might encounter?4

KIDS’ LAB LESSONS

QUESTION How can you use the sun to tell time?

EXPERIMENT OVERVIEW In this experiment you’ll get to build your own sundial. With it, you can keep time the way ancient civilizations did. As the sun rises and sets, it makes shadows of different lengths and angles. You’ll use the location of the sun’s shadow on your sundial to tell you exactly what time it is.

SCIENCE CONCEPT The sun doesn’t actually move around the earth; it only seems that way. Instead, the earth rotates on its axis, so at any one time about half the people on Earth can see the sun and the other half cannot. This is how we get night and day. What a sundial does is track the location of the shadow that the sun makes, and it uses that location to determine the time of day. You have to know a few things in order for your sundial to work. For example, you need to know where true north is, and you need to know where the sun’s shadow will be at certain times of day. Once you have set up your sundial, you should find it to be pretty accurate!

MATERIALS

Sturdy paper plate

Unsharpened pencil

Modeling clay

Compass

Marking pen

sundial: an ancient time-telling device.

PROCEDURE

1.Poke a hole in the middle of the paper plate large enough for the pencil to fit through.

2.Stick the pencil through the plate. Make sure the bottom of the plate is facing up.

3.Place the end of the pencil in a lump of clay below the plate to anchor it down.

4.Use the compass to locate true north and place your sundial in an open space with the pencil pointing slightly to the north. (This method works for anyone who lives in the Northern Hemisphere. If you live in the Southern Hemisphere, you will point the pencil to the south.)

5.5. At 8:00 in the morning, mark on the sundial the location of the pencil’s shadow. Label it “8:00 A.M.” Repeat this step every two hours until sunset. Your sundial is ready!

QUESTIONS FOR THE SCIENTIST

Are the markings evenly spaced?

Do you think it matters what time of the year you build or use your sundial? What happens when the days get longer or shorter?

At what time of day does the shadow of the sun point true north? Is it this way all year round?

FOLLOW-UP Research some of the civilizations that used sundials and think

about these questions:

What were some of the variations they built?

Were any of them like yours?

Why do you think people stopped using sundials?

Look around your town to see of you can find any sundials. Check the accuracy of any you find.

TRY THIS SEASONS IN THE SUN

Another way of measuring time is to mark the changing seasons. From the heat of summer, to cool crisp days in autumn when the leaves fall, to the snows of winter, to the first blooms of spring, seasons show us that time is passing and that we are indeed making our way around the sun. It’s a journey that takes a full year to complete. Many people believe that the reason why it is warm in the summer and cold in the winter is because the earth is so much closer to the sun in the summer than in the winter. However, this isn’t so.

Fun Facts

The earth is actually farther from the sun in the summer (94.6 million miles in June) than in the winter (91.4 million miles in December).

The earth is tilted at an angle of 23º from vertical. This is why we have seasons.

QUESTION

Why do we have seasons?

tilt of the earth: the angle the north and south poles of the earth make with a

vertical line.

MATERIALS

Marking pen

Medium or large Styrofoam ball, available at a craft supply store Desk lamp

without a shade Pencil or long knitting needle

PROCEDURE

1.Mark the top and bottom of the ball with the letters N (on top) and S (on the bottom). These marks indicate the north and south poles.

2.Draw a circle around the middle of the ball to indicate the equator of the earth.

3.Place the lamp in the middle of your room.

4.Push the pencil through the N and S markings on the ball and tilt the top of the ball slightly toward the lamp.

5.Turn the light on and notice what parts of the ball are illuminated. This represents the beginning of summer in the Northern Hemisphere (location I).

6.Notice which wall of the room the ball is tilted toward. You will want to keep the ball tilted toward the same wall throughout the experiment. Move to a position 90º away from your starting position (location II). Again, notice what parts of the ball are illuminated. This represents the first day of fall in the Northern Hemisphere.

7.Now move another 90º around the lamp and again notice what parts of the ball are illuminated (location III). This is the beginning of winter in the

Northern Hemisphere.

8.Finally, move another 90º around the lamp and note the illuminated parts of the ball (location IV). This is the first day of spring in the Northern Hemisphere.

WHAT’S HAPPENING

We have seasons with longer and shorter days not because the earth is any closer to the sun, but because of the tilt of the earth. When the north is tilted toward the sun, the Northern Hemisphere has summer. Days are longer and warmer and you can see this effect if you rotate the ball and notice how long the northern parts of the earth are illuminated. In the Southern Hemisphere, however, little sun reaches the ball. Days are shorter and colder and this is when they have winter. Six months later (location III), the north has winter and the south has summer. You can see how the tilt of the earth gives the south much more sunlight and how the north gets little. In spring and fall, days are about the same length all over the earth. You can see this in locations II and IV.

Sneaky Scientists

Two scientists want to arrange a secret meeting to discuss a new solar energy experiment. Use the sundial decoder to figure out the message that one scientist sent to the other. Write the secret message on the lines provided.

KIDS’ LAB LESSONS

If you look into the sky a little beyond the sun, you’ll see thousands of stars. Some of the stars appear to be connected with other stars, as if they formed a particular shape. In fact, ancient civilizations believed that the shapes formed by stars meant something, and they made up stories about the shapes. The shapes are called constellations. Can you find some of the more common ones?5

QUESTION Why do we see only part of the moon?

EXPERIMENT OVERVIEW In this experiment, you’ll set up a model of the sun, the moon, and the earth and track the phases of the moon through

drawings and a hands-on activity.

constellation: any arrangement of stars in the sky into a familiar shape or

pattern.

phases of the moon: the different portions of the moon that we can see during

its orbit around the earth.

SCIENCE CONCEPT Surprisingly, the same half of the moon always faces Earth. We can never see the “dark side of the moon” except from a spaceship. The only reason we can see the moon is because light from the sun reflects off its surface and back to our eyes.

As the moon orbits the earth (a journey that takes about 29 days), half of it always faces the sun. However, it isn’t always the same half! So as the moon travels around the earth, we see any amount from 0 percent of the side that faces us to 100 percent of that side. These percentages are called the phases of the moon.

Formally, the phases are labeled as new moon (we can’t see it), first quarter (we see the right half), full moon (we see the entire face), and third quarter (we see the left half). Every once in a while, the moon during its “new” phase crosses the line between the sun and the earth and we experience a solar eclipse. Not as rare are lunar eclipses, when, during the moon’s “full” phase, the earth passes between the sun and the moon and casts a shadow on the moon.

Fun Facts

There are 88 constellations recognized by astronomers.

MATERIALS

Current newspaper

Paper plate

Marking pen

Desk lamp as bright as possible, without a shade Small ball, a little larger than your hand Clean sheet of paper Time (This experiment will take up to a month to

complete, but only requires a few minutes each day.)

PROCEDURE

1.Check in your local paper to find the date of the new moon. Start your experiment on this day.

2.On the paper plate, draw marks around the outer edge representing 28 days. You might want to draw lines that cut your plate in quarters and make seven marks per quarter of the circle. You will use this as your guide for locating the ball when you begin your experiment. Start at 0/28 and begin numbering in a counter-clockwise direction.

3.Set your lamp on the side of your room against one wall. Make sure this is a location you can easily keep the lamp or place it each day for your test.

4.Turn off the light in your room and turn on the lamp.

5.Set the plate on the floor in the middle of your room and stand on it. Point Day 0/28 toward the lamp.

6.Face in the direction of the day you are recording (beginning at Day 0 and counting upward for 28 days) and hold your ball at arm’s length.

7.Take a close look at the illumination of the ball. For Day 0, there should be no illumination, as this corresponds to the new moon.

8.Record the ball’s illumination on your sheet of paper in a table that allows you to track the phases of the moon over the course of one month.

9.Repeat this step each day for 28 days. When you finish, you should have 29 drawings (Day 0 through Day 28) showing the phases of the moon.

10.Periodically, check your results with the actual moon outside at night.

Fun Facts

The moon actually looks a reddish color during alunar eclipse due to sunlight passing through the earth’s atmosphere and being bent toward the moon — in effect, a “sunset” during an eclipse.

QUESTIONS FOR THE SCIENTIST

Did your drawings match the actual phases of the moon?

What effect did the fact that the moon’s orbit is actually a little longer than 28 days have on the accuracy of your data?

What does the fact that solar and lunar eclipses are rare tell you about the orbit of the moon? Think about how this would look in your experiment.

FOLLOW-UP Research the history of man’s attempts to fly to the moon. What objects were left on the moon by those who visited? For a powerful look at a failed moon voyage that almost cost three astronauts their lives, rent the movie

Apollo 13.

Giant Science Kriss-Kross

How can you find the answers to these science questions? If you’ve looked through all the chapters in this book, you will have no problem! Fill each answer into the numbered grid. The words in the shaded row will answer this riddle:

What is the best part about being a scientist? We left you a few A-T-O-M-S to get you started. Need more help? Check out the Experiment Overviews.

Clues:

1.A mixture of two or more liquids.

2.Animals use _____________ to blend into their surroundings.

3.When you heat air in a bottle, you can _____________ a balloon.

4.Scientists use this form of energy to light up their laboratories. You use it at home, too!

5.Isaac ___________ is the scientist who defined the laws of gravity.

6.A _____________ points toward the magnetic north.

7.The sun gives us _______ in the form of heat and light.

8.A process that uses one metal to coat another metal.

9.An ___________ is a picture that shows you the inside of your body.

10.Barometers are devices used to measure air __________.

11.Albert _________ is a scientist whose theories and experiments led to new ways of thinking about time, space, matter, energy, and gravity!

12.One of the Laws of Motion says that every action has an equal but opposite

_____________.

13.___________ only form when it is cold enough for water to freeze, but at the same time there is a way for water to drip.

14.Electricity flowing through a wire turns the wire into an electro___________.

15.A seismologist is a scientist who uses a Ricter Scale to measure the strength of __________________.

16.The _________ _________ (2 words) controls all the actions and reactions of the body.

17.An astronomer is a scientist who uses a __________ to look at the stars and planets.

18.A ___________ grows up from the ground.

SCIENCE FAIR PROJECT: EARTH SCIENCE

RIVERS

Think about the last time you looked at a river — really looked at it. Was it straight, or did it bend and curve, and maybe even wind its way through town? The more you look at rivers, the more you might wonder why they aren’t straight. They start in the mountains and run to the sea. It sounds like a simple path, one that they should have carved out early in their lives and never deviated from. However, the paths of rivers have surprised and intrigued people for thousands of years. When a time of flooding comes to an area, the path of the river becomes a topic for even more discussion. It’s almost like a river has a

mind of its own!

QUESTION

Why aren’t rivers straight?

EXPERIMENT OVERVIEW

In this experiment, you’ll first get to build a mountain. To do that, you’re going to need some mountain supplies and a pretty open space for the water to flow out. You’re also going to need plenty of water, so plan ahead. You’ll have two options to choose from, in terms of the “rain” that falls: steady or occasional. Each pattern will result in a different set of rivers, so you might even want to try both.

SCIENCE CONCEPT

When water flows down a mountain, it finds the quickest path to the bottom,

even if that path isn’t straight. Trees, rocks, and hills cause it to change direction and the speed it travels. When water moves slowly, it tends to dig away at its boundaries (the riverbank), and sometimes will cut out a piece of the bank, which makes the river a little wider at that point. Every time the river changes, the water flow changes and that causes even more variation in the path of the river. So over time, a river can carve out all kinds of interesting paths to the sea. But that’s not all. When a new piece of the river is carved out, the current carries rocks and dirt farther downstream. Where this material lands, the river gets shallower. That is why the mouths of rivers, especially where they empty into the ocean, tend to be really wide, open, and flat, with water that moves slowly into the ocean.

MATERIALS

A large mountain of rocks, dirt, sand, mud, and so forth, at least 3 feet high An open place where the rivers can flow and deposit the mud they accumulate as they flow down the mountain Plenty of water, either through a hose, a sprinkler, or a watering can Camera

PROCEDURE

1.Make sure the mountain is not the same all over. There should be obstacles all over it that will encourage the water to flow in interesting paths.

2.Predict where the rivers will form.

3.Choose a method of watering:Steady rain — Use a sprinkler on top of the mountain, or very near the edge of it to produce rainfall that will be steady throughout the experiment. A helpful assistant could simply hold a hose above the mountain or spray the water onto the top of the mountain. You may need to experiment to find what works best.Occasional rain — Use a watering can, a pitcher of water, or a short interval of rain from a hose. If

you choose this method, you will need to return every hour or so to add more water. This allows the mountain to absorb some of the water and will result in a different set of rivers.

4.Begin watering the mountain.

5.If you are using a steady rain, take a picture before you begin, and then take a picture every 5 to 10 minutes until the rivers are no longer changing. Your goal is to observe the changes in the mountain over time. It’s better to have too many photos than to have too few.If you choose the occasional rain method, take a picture before you begin and then during each rainfall. Apply the water for as long as you have chosen and then let the mountain sit until the next session. Repeat applications until the rivers stop changing. This method will likely take quite a bit longer than the other, but might give a more accurate depiction of true rainfall.

6.Keep a record of your method and the photos you took.

7.When you get the photos developed, you should have a record of the progress of the rivers you produced. If you find that the photos don’t show enough change, use every other picture.

QUESTIONS FOR THE SCIENTIST

Did the rivers form in the places you predicted?

How much material was carried off the mountain to the surrounding area?

Did you see any smaller rivers merge into larger rivers?

Was there one river that changed its path more than the rest? If so, what were some of the characteristics of that river that made it change so much?

CONCLUSION

Each time you repeat this experiment, you will get a different result. That’s part of the fun of science! Now that you’ve produced your own rivers, see if you can visit a local river and identify places where it veered over time, where it moves faster or slower than other places, and any obstacles that might affect the flow of water. Also, see if you can trace the source of the river, although it might be many miles away in the mountains.