The use of wood for cooking is one of the main causes of desertification in many countries. One of the hardest tasks of women in poor countries is to find fuel for cooking. In these countries, the ashes and smoke produced by burning wood or cow dung are among of the main causes of eye disease among women. Water borne diseases are a major cause of mortality in developing countries. Therefore, providing the population of poor countries with solar ovens to boil water and cook food could be a successful strategy for improving the quality of life and for solving some of the most urgent environmental problems.
A main difficulty in promoting the use of solar energy for cooking is the lack of knowledge on the part of the population about these methods. Another difficulty is the cost of the solar ovens, which ca be very high for poor populations. The solution could be to train the population for to build solar ovens using cheap materials.
I had the opportunity of visiting two exhibitions presenting materials for scientific experiments built by pupils using recycled materials. They were organized by the Ministry of Education of the Palestinian National Authority in HePon and Ramalha.
Magnifying glasses built with a lamp and olive oil or a candle and two stripes of metal in order for show the transformation of heat into electric currents were part of the hundreds of presentations.
Some of the experiments were related to the transformation of light energy into heat. For example, a solar oven built using small fragments of mirror, a solar water heater consisting of black tubes and a solar oven made from transparent plastic, and a black box were also presented. The proposed devices were very simple and made it very easy to measure the temperature of water and to write down the results.
These "easy to understand - easy to do" experiments are useful for teaching about the transformation of energy. They are laso useful for teaching about how to use cheap materials for solving da-to-day problems, such as how to cook food or boil water.
They also promote the teaching of science without using expensive instruments, a solution for improving science teaching in poor countries.