Single-sex education, also known as single-gender education, is the practice of conducting education where male and female students attend separate classes or in separate buildings or schools. The practice was common before the nineteenth century, particularly in secondary education and higher education. Single-sex education in many cultures is advocated on the basis of tradition as well as religion, and is practiced in many parts of the world. Recently, there has been a surge of interest and establishment of single-sex schools due to educational research.