sentences:  Spanish students aged six to sixteen undergo primary and secondary school education, which are compulsory and free of charge.Successful students are awarded a Secondary Education Certificate, which is necessary for entering further (optional) education as is Bachillerato for their University or Formacion Professional (vocational studies).Once students have finished their Bachillerato, they can take their University Entrance Exam (Pruebas de Acceso a la Universidad, popularly called "Selectividad") which differs greatly from region to region.