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Teaching for a Better World |
Making Solar Box Cookers |
Thousands of years ago the Greeks and Romans realized that the sun is the great source of heat and light for our world. They designed their homes and cities so that all would benefit from its inexhaustible energy. The sun was at the heart of their lives.
Today, however, our students sometimes take for granted the energy we receive from the sun, and in many instances are truly not aware that it is the original energy source for most of our daily activities. A flick of the switch gives us light; a turn of the thermostat gives us warmth for our homes; a twist of the knob gives us heat to cook. For most of these activities we are burning fossil fuels and polluting the earth.
Many days can be spent with the students discussing the effects that the burning of fossil fuels has on our world. The next step is then to ask: What can we really do about it? How can we meet our needs for light and heat without creating pollution? Students are well aware that the sun is a source of light. And they know that the sun can also give them heat... a gentle warmth on a cool day. But have they discovered the adventure of cooking with the sun?
Students will at first be very skeptical about the possibility of actually cooking a hot dog, baking cookies or making pizza using only the heat of the sun; but with a solar box cooker they will soon learn that this seemingly impossible task can be accomplished. A solar box cooker is simply a shallow (about one foot deep) container with an aluminum foil interior, glass or plexiglass top and a reflector lid. The theory behind the cooker is simple: trap the energy of the sun in a container long enough to cook food.
Most solar box cookers are so simple that they can be built by school children. There are many different ways to build one. Once students have seen for themselves just how high temperatures can get in a solar cooker (200 to 300 degrees F), they may then be able to think of ways in which the oven may be improved. This is a great opportunity for students to use their creativity. Encourage them with questions like: Which type of oven would work better, shallow or deep? Would it help to insulate the oven? Would painting or covering the outside with a certain color improve the oven? Would adding more reflectors help? What about a totally different design? (You may want to suggest using a cardboard pizza box or a potato chip can with a silver metallic interior.)
Once you have sparked your students' imaginations the possibilities are endless. Have students build their own models implementing their ideas for improving the solar box cooker. Using oven thermometers to measure the temperature, hold a contest to see which model heats up fastest or reaches the highest temperature.
The most fun of all comes when you actually cook food. Try out some simple things first: cookies, hot dogs, nachos. You may wish to have students experiment with different recipes. What cooks best in the solar cooker? Will food cook more quickly if it is in a black container? The opportunities are endless for experimentation. Once students realize that cooking with sunlight is both easy and fun you may want to capitalize on this enthusiasm by holding sun bake offs or solar-cues. Invite other students and staff to experience first-hand the sun's cooking power by sharing your sun-cooked foods. You may also wish to raise money for environmental causes by selling the items that the students have cooked in their own solar box cookers. But the heart of the lesson should center on how we are helping the environment. Cooking with sunlight is pollution free. There's no fuel to buy, no trees to cut down. It is not create a fire hazard and there are no ashes to clean up.
Of course, how often you are able to use your solar box cooker is dependent upon how much sunshine you get in your part of the world. The topic of solar geography can itself lead to investigation and discussion.
Have older students create maps showing the amount of solar energy received in various parts of the world. This study should lead them to discover that many parts of Africa, Asia and Latin America receive abundant sunshine. Half of the world's families live in these parts and most live in deep poverty. They depend on wood to cook their food, and in many of these countries trees are being cut down and used up faster than they can grow back or be replanted. The loss of trees leads to soil erosion and loss of habitat for wildlife, creates air pollution, adds to global warming and reduces an important source of oxygen. By using a solar cooker, which cooks year round in the tropics, families can cut their use of wood in half. This greatly saves trees and drastically reduces local pollution. And your students can be a part of this experience. Have your students become sun pals with kids from a developing nation. My students corresponded with several different classes from The Gambia in West Africa. We exchanged letters and photos and lifelong friendships were formed; we were also able to raise enough money to send some solar box cookers to our friends in their village in West Africa.
The experience was truly global and most unforgettable. Solar energy is what makes life possible on earth. Just as the Greeks and Romans did so long ago, many are turning to solar energy today because it is a clean, renewable fuel. There's much that solar energy can do already, yet much more left to be discovered. Just maybe one of your students will become the scientist who makes one of those discoveries.
Additional Sources of Information
The Solar Cookers International Web site contains a wealth of information on solar cooking.
Arizona Energy Office. A Day in the Sun, 1991, an 18-minute video filmed at a solar cooker cookout in Tucson, Arizona, shows the range of solar cooker technologies and demonstrates cookers being used for a variety of foods. The cost is $24.95 from the Arizona Energy Office, 3800 North Central, Suite 1200, Phoenix, AZ 85012, (602) 280-1402.
Florida Energy Office. Renewable Energy Activities for Middle Grades, free from Florida Energy Office (within the Department of Community Affairs), 2740 Centerview Drive, Tallahassee, Florida 32399-2100, (904) 488-2475.
Cooking With The Sun Halacy, Beth and Dan. Lafayette, CA: Morning Sun Press, 1992, 114 pages, ISBN 0-9629069-2-1. Available in the US for $7.95 from Pitsco, PO Box 1708, Pittsburg, KS 66762, 1-800-835-0686; in Canada, $12.75 plus $2.75 from Advanced School Equipment, 5029 49th Avenue, Ponoka, AB T4J 1S8, 1-800-465-7737.
Solar Cookers International is a non-profit organization devoted to promoting solar cooking internationally as one solution to deforestation and desertification. Membership is $38; a subscription to their interesting quarterly newsletter The Solar Cooker Review is $10/year; and an instruction guide, How to Make and Use a Solar Box Cooker, costs $5. They also sell pre-fab cookers, both the solar box type and a new and simpler design that uses only foiled cardboard cleverly folded into a parabolic sun trap. Ask for instructions to make your own. Contact Solar Box Cookers International, 1919 21st St. Suite 101, Sacramento, CA 95814, phone 916 455-4499, fax 916 455-4498, email sci@igc.org.
SunLightWorks has published several books on solar energy applications, including Solar Cooking Naturally (ISBN 09634696-0-1) contains over 100 recipes for solar cookers; The Expanding World of Solar Box Cookers (ISBN 0-96326740-X) covers principles and theory in designing solar box cookers with local materials; Sunlight Works: Solar Science (ISBN 0-9634694-2-8) is a 32-page activity guide on solar energy principles for students aged 8-12. The books are $10 each plus from SunLight Works, PO Box 3386, Sedona, AZ 86340, (520) 282-1344.
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