In Mexico, the educational system is divided into three steps: primary school (primaria), junior high school (secundaria), and high school (preparatoria) . Secundaria is the middle school level and is compulsory by law. It comprises grades 7-9 and is part of the basic compulsory education system, following primary school and coming before high school. Students attend one of three shifts: matutino, vespertino, and nocturno. At this level, more specialized subjects may be taught such as Physics, Chemistry, and World History. There is also the técnica which provides vocational training, and the telesecundaria which provides distance learning.