In Slovakia the content of sex education varies from school to school, most frequently as a segment of a larger lesson plan of a subject akin to "Nature science" in English (this course covers both biology and petrology). Generally the sex ed content taught in Slovakia is quite basic, sometimes lacking, though exactly what any given lesson contains varies among schools and is dependent on the teacher's knowledge of the subject. It is not uncommon for teachers to rely on students asking questions (as opposed to documentaries, discussions, textbooks and in-class debates). Classes are usually divided into boys and girls. Boys are taught the basics of sex, usually limited to dialogue between student and teacher of annotated diagrams of genitalia; while girls are additionally taught about menstruation and pregnancy.