Read correspondence between our mentors from Cool Careers and students. Contaminated Water Project Class 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? Mentor For test kits try a company called HACH. Here is an Internet site to look at: http://www.hach.com/h2ou/h2twss99.htm#Hach Also you might try some swimming pool chemical test kits. Class 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? Thanks. Mentor 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 methods. 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? Roger Watershed Project Mentor Hi y'all, 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! Class 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? Mentor Have you looked here? http://map2.epa.gov/enviromapper/ How about ? http://terraserver.homeadvisor.msn.com/default.asp Wetlands Project Mentor Dear teachers, 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. America's Wetlands 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, and towns. 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. Class Can food grow in wetlands and what kind? Mentor 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 Class 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. Mentor 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. Composting Project Mentor 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% water. 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 at http://www.statlab.iastate.edu/soils/nssc/nsscprod/surdown.pdf Mentor Composting is the biological decomposition of organic wastes to form humus, a dark brown, porous, spongy, earthy smelling substance. 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 gardens. 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 Class 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. Mentor 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: http://www.wri.org/wri/wr-98-99/urbanair.htm http://www.cleanerandgreener.org/GEP/slideshow/sld012.htm (and the slides that follow it) http://www.nrdc.org/air/pollution/ http://www.epa.gov/OMSWWW/ http://www.epa.gov/globalwarming/ http://www.ucsusa.org/index.html 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. Class 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 electricity. Class 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? Mentor 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. Class How many cars in the world are solar? Mentor 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 range. You can find more information on the Department of Energy's web site at http://www.eren.doe.gov/consumerinfo/refbriefs/db2.html Class If we use solar cars how would we use them at night? Mentor 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 Class Are computers or televisions that are energy efficient more expensive? Mentor 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 that’s what I told my kids). Class How long does it take to build an energy-efficient home? Mentor 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. Class Can you build energy-efficient homes without using solar power? Mentor 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. Class Can cars use the sun's energy instead of gas? Mentor 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. Class How much does it cost to make an energy-efficient home? Mentor 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. Class What types of things can teenagers do to save energy? Mentor 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. Class 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? Mentor 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. Class What are photovaltaic cells? Mentor 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. Class How can a family living in an energy efficient home give back all the electricity they don't use to the electric company? Mentor 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. Class With teenagers, what do you think are the most difficult behaviors to change, in terms of becoming more energy efficient? Mentor 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 don’t think about these things. So, before they leave a room they need to look back and see what is on, then turn it off. Home | Cool Careers | Hot Topics | Class Projects Glossary | Resources | Credits Thirteen Ed Online | Educators | Students | Parents/Caregivers Thirteen Online