|Read correspondence between our
mentors from Cool Careers
Contaminated Water Project
Do you have any suggestions on how to go about researching and
acquiring water testing kits that are reliable and can be used
by the average, non scientific teenager?
For test kits try a company called HACH. Here is an Internet
site to look at:
Also you might try some swimming pool chemical test kits.
My 8th grade students have established 'research stations' at
the small lake we will be focusing our project on, henceforth
"Nacoochee Lake.' We began chemical tests last week, and have
found some interesting, and confusing, data. First, we are using
two different methods to measure pH, a Lamotte wide-range pH
kit, which uses phenolpthalein as an indicator, and standard
pHydrion dipsticks. In our tests today, the kit showed a pH
of 7-7.25, depending on location, while the strips showed a
pretty distinct reading of 5. Any ideas as to why this may be
happening? Also, in testing for alkalinity, again with a standard
Lamotte kit using the titration method to measure calcium carbonate,
our results seem REALLY low, in the area of 20-24 ppm. How might
this be explained? Is there a standard for lakes and ponds?
First, the pH test kits you are using are notoriously unreliable.
But they are OK for teaching and to get a general idea of pH.
I suggest you try to repeat your measurements, trying to keep
the sampling conditions the same, and see if you get scatter
in the pH results. This can be an interesting exercise, and
will give your students some confidence or lack of in the test
When we look at "contaminated water", we use much better methods,
which also happen to cost a lot of money! In fact, there are
very detailed water sampling "protocols." They describe exactly
where and when and why you are sampling. How you prepare the
sampling equipment to ensure that it is clean. Exactly how you
reach into the water and scoop a sample, how soon you have to
cover it, or maybe preserve it by adding another compound. And
so on... About the alkalinity -- there is no standard. Your
results show a relatively acidic lake. Does that make sense
based on where the lake water comes from?
What is the difference between a watershed and a catchment?
Answer: none! Catchment is what the Brits call it (and Canadians
and Aussies too). So do an Internet search on catchment!
My class is beginning our research project by finding out where
our watershed is. We have found conflicting information putting
us in the Arthur Kill and the Raritan watersheds. We are in
Woodbridge. Can you tell us which watershed is our watershed?
Have you looked here? http://map2.epa.gov/enviromapper/
How about ? http://terraserver.homeadvisor.msn.com/default.asp
Each week, I will provide excerpts from Web sites and articles
on America's wetlands. Wetlands are marvelous natural laboratories
for children and adults alike. Best of all, there is probably
a wetland within walking distance of your school! This week,
I am posting an excerpt from the US Environmental Protection
Agency's Web site: http://www.epa.gov/OWOW/wetlands/vital/wetlands.html
Please visit the Web page for beautiful color pictures of wetlands
from around the country.
Wetlands are indeed the vital link between water and land. "Wetlands"
is the collective term for marshes, swamps, bogs, and similar
areas found in generally flat vegetated areas, in depressions
in the landscape, and between dry land and water along the edges
of streams, rivers, lakes, and coastlines.
Wetlands can be found in nearly every county and climatic zone
in the United States. Most likely, a wetland exists in your
neighborhood or very close to it.
Because they are so varied, wetlands can be difficult to recognize.
Some are wet all of the time; some may look completely dry most
of the time. Our ideas of what a wetland should look like may
not include all types of wetlands. Some wetlands are large and
some are very small. Many have been altered by human activities
such as farming, ranching, and the building of roads, dams,
Wetlands have often been regarded as wastelands-- sources of
mosquitoes, flies, unpleasant odors, and disease. People thought
of wetlands as places to avoid or, better yet, eliminate. Largely
because of this negative view, more than half of America's original
wetlands have been destroyed-- drained and converted to farmland,
filled for housing developments and industrial facilities, or
used to dispose of household and industrial waste.
As people understand ecological processes better, attitudes
towards wetlands change. We now know that wetlands are, in fact,
valuable natural resources. Whether drier or wetter, bigger
or smaller, wetlands provide important benefits to people and
the environment. Wetlands help regulate water levels within
watersheds; improve water quality; reduce flood and storm damages;
provide important fish and wildlife habitat; and support hunting,
fishing, and other recreational activities. Wetlands are natural
wonderlands of great value.
Can food grow in wetlands and what kind?
The answer is yes. One example is rice, which is grown, as you
know, with its root system submerged in water. Another example
is the beast known as a crawfish. See also for example http://www.iucn.org/themes/pmns/collaborative/hnwcpiied.html
Invasive Species Project
We were wondering if invasive plant species or animal species
are more destructive. We were thinking about the zebra mussel
that has spread all the way into the Ohio River.
You ask a very good question to which there is not an either/or
answer. Plant AND animal species can be equally destructive
-- it depends on the habitiat they occupy and their numbers.
For example, in wetlands an invasive plant called purple loosestrife
is driving out native species such as cattails. There the plant
is the problem. In the east and the midwest, the Asian Longhorn
Beetle is destroying forest and city trees. There the insect
is the problem.
So the answer to your question is that invasive plants AND invasive
animals are equally problematic.
Great civilizations generally had fertile soils. The annual
flooding by the Nile River and the good soils of the "Fertile
Crescent" located between the Tigris and Euphrates Rivers
gave rise to the Egyptian and Mesopotamian civilizations. The
scientific reason for these good soils or fertility was unknown
until many centuries later. We realize now that the river flooding
deposited soil that was rich in nitrogen and phosphorus as well
as organic matter making it suitable for the large-scale food
production necessary to support a stable localized population.
Soil is important from many standpoints but primarily from an
agricultural one. Topsoil, the upper surface soil in which plants
grow, is a mixture of minerals, organic matter, air, and water.
A good mixture for plant growth has been found by volume to
consist of 45% minerals, 5% organic matter, 25% air, and 25%
While soil nutrients such as nitrogen and phosphorus are important,
the organic component should not be ignored. The organic matter
in topsoil is made up of partially decayed and partially synthesized
plant and animal residues. Since this material is constantly
being used up by soil microorganisms, it must be renewed constantly
by the addition of plant residues. Compost or biosolids can
also serve this purpose.
Although the organic matter in topsoil makes up only 3-5% by
weight, its value for plant growth is far greater. Without it,
the biological activity in the soil would stop. It also helps
plant growth by allowing it to hold moisture near its roots
during dry conditions and by storing nitrogen for gradual release
during the plant's growth cycle.
For additional classroom information on soil types, lessons,
demonstrations in soil science, and information on your state
soil (yes, there is a state soil just like official state flowers
and state birds), you can click onto the U.S. Department of
Agriculture's Web site at http://www.statlab.iastate.edu/soils/nssc/educ/Edpage.html.
Another useful U.S. Department of Agriculture website is found
Composting is the biological decomposition of organic wastes
to form humus, a dark brown, porous, spongy, earthy smelling
Composting can be done by individuals and families. It is one
of the best ways not only to recycle household and yard wastes
but also to produce something that has a benefit to lawns and
Forms of composting have been practiced for thousands of years
to increase crop yields. It was used by the ancient Roman, Greek,
and Chinese civilizations as well as by American colonists such
as George Washington and Thomas Jefferson. Generally, these
involved using animal wastes and manures.
Traditional composting is done in well-ventilated bins. Finished
compost can be produced in anywhere from a few weeks to a few
months depending on such variables as mixing frequency, temperature,
moisture and types of wastes used. Experts generally recommend
to beginners that they add equal amounts of brown wastes
(fall leaves, straw, dried grass, wood scraps) and green
wastes (kitchen scraps, coffee grounds, green grass, flowers)
to the bin in order to get a good compost product. Brown wastes
contribute the necessary carbon component while green wastes
contribute the required nitrogen component.
You can see how one middle school class established its own
composting project and reduced the amount of waste generated
by the entire school by clicking onto http://www.mansfieldct.org/schools/mms/compost/
Solar Cars Project
We are having difficulty finding the impact that energy consumption
would have on air pollution, We have out own thoughts and ideas,
but we can not find proof.
Energy production and use are key contributors to air pollution.
Pollution from power plants and cars can cause health problems.
And carbon dioxide emissions from the burning of fossil fuels
trap infrared radiation that the Earth is emitting to space.
This causes global warming, so this can also be considered pollution
of a sort. Check out these web sites:
(and the slides that follow it)
There is an especially good page on the Environmental Protection
Agency Web site that responds to some of the arguments certain
people have made to discount global warming. (The great majority
of atmospheric scientists believe it is a major problem, but
a small minority argues against it. The people in the minority
are called "greenhouse skeptics.") Check out this
web site: http://www.epa.gov/globalwarming/faq/moredetail.html.
Can ordinary appliances be hooked up to the batteries in a home
that used solar power only? How do you transfer electricity
from the solar panels to the electric devices?Mentor
Good question. Photovoltaic (PV) panels provide direct current
(DC), as do the batteries that store their electricity. Household
appliances run off alternating current (AC). Solar PV systems
use devices called inverters that convert the DC to AC, so they
can power ordinary appliances. However, PV systems are still
pretty expensive, so to reduce the size of the PV array needed
on a house, it makes sense to pay a little bit more money for
the appliances and purchase very energy-efficient ones. The
power consumed by refrigerators, washing machines, TVs, etc.
can vary greatly from one model to another. This power consumption
is a critical consideration if you use solar energy to provide
We made a model of a solar car with a photovolatic cell but
it seems like it will be hard to keep the speed regulated in
a solar car. Is this a huge problem?
Full-size solar cars have a device called a speed controller.
This adjusts the amount of electric current sent to the DC (direct
current) motor. The speed controller allows the driver to control
how fast the car goes.
Your model car doesn't have a speed controller. But the speed
of the motor will depend on how much sunlight strikes the photovoltaic
panel. Try using a reflector to reflect extra sunlight onto
the PV panel and make the car go faster. Or use a semi-transparent
material to block some of the sunlight and slow the car down.
How many cars in the world are solar?
Cars that run directly and completely off sunlight have only
been built for research and development and for education. They
have not been developed for transportation because the amount
of sunlight striking a vehicle's surface provides a relatively
small amount of energy. But teams of university students and
manufacturers have built hundreds of solar cars in recent years
for entry into races. Designing a car to run on such a small
amount of energy teaches students a great deal about how to
make a car more energy-efficient. (You are also learning a lot
about car design as you build your model solar cars.)
The batteries in non-solar electric cars are generally charged
between trips from a power supply plugged into a conventional
electric outlet. But the source of electricity for battery charging
can also be solar energy, namely photovoltaic panels that are
not attached to the car. Also, one company has developed an
electric car that uses PV panels on the roof to provide extra
charge to the battery on sunny days and extend the car's driving
You can find more information on the Department of Energy's
web site at http://www.eren.doe.gov/consumerinfo/refbriefs/db2.html
If we use solar cars how would we use them at night?
As you might expect, solar cars have a problem when the sun
isn't shining. However, they can continue to run for some period
of time depending on the size of the battery they have and how
well it was charged up during the day. While the battery in
your family car is just used to start your car, the battery
in a solar car is used to actually run the car when the available
solar energy is inadequate.
So just as with non-solar electric cars, the batteries are very
important, and a lot of research is being done to find ways
to lower their cost and weight and to improve their performance.
Energy Audit Project
Are computers or televisions that are energy efficient more
The computers and televisions that are on the market today are
far more efficient that those produced just a few years ago.
At first these were more expensive but over time the large quantity
of these products sold has brought the prices down. The energy
efficient feature is that they shut themselves off after a period
of non-use. When computers first came into use in the home,
it was widely believed that it was more efficient to leave a
computer running than to turn it on and off. That was never
true, but today the computer will go into sleep mode and save
energy even if they are left on. I still say turn them off overnight.
Televisions should always be turned off when you leave the room
for more than a few minutes. Also, if you turn off the television
your grades will go up (at least thats what I told my
How long does it take to build an energy-efficient home?
The time it takes to build an energy-efficient home is just
slightly longer than a production home with standard features.
The extra time comes in the coordinating of sub-contractors
to do the work at the right time. In general it might take an
extra two to three weeks to build an energy-efficient home.
If we are adding exotic (features that are not common) technologies
such as photovoltaic cells to the roof or specialized insulation
or heating systems the time can be longer. Because there are
fewer people who do the work scheduling becomes more difficult.
Also, some of the products need to be ordered and could take
longer to receive.
Can you build energy-efficient homes without using solar power?
Yes! Solar energy is only one component of an energy-efficient
home. The use of solar energy to power appliances and generate
electricity is a very expensive system to install and requires
a south facing roof or structure as well as modifications to
your electrical system. In new homes this can be done easier
than in older homes. But, the use of solar lighting in landscaping
and with outside porch lights is a good way of using solar energy
at an affordable price. Many new commercial and industrial building
are being built with photovoltaic cells to generate electricity
because they can sell back to the electric company the energy
not used in the structure. It is a win-win situation.
Can cars use the sun's energy instead of gas?
Yes! But the technology is still evolving. The trick is storing
the energy captured by the cells. Battery technology is developing
quickly and we are starting to see more efficient ways to store
and captured the energy. For instance, in the solar powered
cars being developed today the cars take the heat generated
by the brakes and redirect it back into the batteries. Every
bit of energy is utilized. I am a sponsor of a local high school
solar program that has competed against colleges and car manufacturers
and has done very well. If you want to check out their car and
program there web site is http://www.lasv.org/LASV2002/index.html.
How much does it cost to make an energy-efficient home?
The cost of building an energy-efficient home depends a lot
on the number of features built into the home. The home that
our construction trades program is building right now will feature
many energy saving features without increasing the cost of the
home very much. We estimate the additional cost will be about
$5,000 on a home that will sell for about $200,000. When you
add features like ground source heat pumps, solar heating or
photovoltaic (PV) cells, the cost goes way up. A builder in
San Diego is building an entire track of homes with some of
these features and is asking about $20,000 more for the homes.
The extra money will be paid back through energy savings over
the next tens years.
What types of things can teenagers do to save energy?
Teenagers can do a lot to save energy. It is amazing how much
can be saved through habitual kinds of changes. Things like
turning off the television when you leave the room, changing
out bulbs to compact fluorescent or just turning off lights
can save a great deal of energy if we all do it. We began a
project at our school this last year where we challenged students
and teachers to make changes in the way they used energy and
the results were terrific. We asked that they unplug their small
refrigerators and electric heaters and turn off lights and computers.
Additionally, we made some minor changes to our facility like
changing light bulbs to compact florescent and we saved over
$14,000 in five months. We found that the schools that were
participating in the project all saved 7% to 20% in energy over
the same period. If you want to know more about the Green
Schools program their web site is http://www.ase.org/greenschools/index.htm.
Good questions! I hope I shed some light (pardon the pun) on
your energy issues.
We learned from the WNET video that zero-energy homes use the
ground for a source of heat. What can they use for cold air
on a hot summer day?
Good question. If they are using a ground source heat pump system,
the same system can be used for both heating and cooling. It
is expensive on the installation but very inexpensive to run
compared to conventional systems.
What are photovaltaic cells?
Photovoltaic cells are silicone cells that range in dimension
(usually about 3 sq.) that absorb energy from the sun
and turn it into electricity. The trick is storing the energy
in batteries. Photovoltaic cells are usually used on roofs and
they power devices that would generally be powered by the power
company. They are very effective with low voltage appliances
such as lights or small motors. It takes one or two cells to
generate one volt of electricity depending on their efficiency.
How can a family living in an energy efficient home give back
all the electricity they don't use to the electric company?
The electric panel that the electric company reads every month
can be equipped with a device that allows energy to flow both
directions. When the house is generating electricity in excess
of that which it uses, the energy flows back into the grid.
Think of it as a water pipe that delivers water. The energy
is put back into the pipeline for someone else to use.
With teenagers, what do you think are the most difficult behaviors
to change, in terms of becoming more energy efficient?
Without a doubt the most difficult is turning off appliances.
Televisions, computers, lights and electric games need to be
turned off when not in use. Because teenagers are always in
a hurry, they dont think about these things. So, before
they leave a room they need to look back and see what is on,
then turn it off.
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