The time of Islamic festivals is calculated according to local sightings of various phases of the moon and the dates given below are approximations which are subject to change each year.
There is a vastly extended network of rivers in Iran most of which seasonally are filled with water. Some permanent rivers run from the Alborz or the Zagros to the Caspian Sea, Persian Gulf and Oman Sea.
Having the world's youngest population, the Islamic Republic of Iran bears the responsibility of educating more than 18 million students at segregated schools.