How much water is needed for plants, animals and people for household needs, what needs to be done to make the air cleaner and where to throw wrappers of chocolate or ice cream - about this and not only experts from the Central Territorial Administration of the Ministry of Ecology and Natural Resources of the Republic of Tatarstan told schoolchildren of 2-3 grades of Russian-Tatar secondary school No. 97of the Privolzhskiy district.