The diminishing of biodiversity constitutes one of the most serious environmental problems of our time. Water, atmosphere and nature as a whole do not recognize borders. Many species, especially birds, fish and mammals, move about over enormous areas ignoring the frontiers between the various countries. The same applies for pollution. Many human activities have a harmful effect on biodiversity beyond the country in which these activities are carried out. Acid rain and spills is a couple of sad examples. In addition, the development of international trade and tourism exerts pressure on natural resources. Schools may integrate biodiversity activities in all subjects, and together with a specialist, study the biodiversity of their community and country, so that pupils become aware of the value of conservation and the dangers that threaten it.