The Primary Certificate Examination (1929–1967) was the terminal examination at this level until the first primary-school curriculum, Curaclam na Bunscoile (1971), was introduced, though informal standardised tests are still performed. The primary school system consists of eight years: Junior and Senior Infants, and First to Sixth Classes. Most children attend primary school between the ages of 4 and 12 although it is not compulsory until the age of 6. A minority of children start school at 3.