there used to be many rules on uniforms and haircuts, although now only uniforms remain partially enforced, and education stress is highly increased. Like in primary school, students spend most of the day in the same homeroom classroom with the same classmates; however, students have different teachers for each subject. Teachers move around from classroom to classroom, and few teachers apart from those who teach special subjects have their own rooms to which students come. Homeroom teachers (담임 교사, RR: damim gyosa) play a very important role in students' lives. Most middle school students take seven lessons a day, and in addition to this usually have an early morning block that precedes regular lessons and an eighth lesson specializing in an extra subject to finish the day. Unlike high school, middle school curricula do not vary much from school to school. Korean, Algebra, Geometry, English, social studies, and science form the core subjects, with students also receiving instruction in music, art, PE, Korean history, ethics, home economics, secondary language, technology, and Hanja. Which subjects students study and to what extent may change from year to year. All regular lessons are 45 minutes long. Before school, students have an extra block of 30 minutes or longer that may be used for self-study, watching Educational Broadcast System (EBS) broadcasts, or for personal or class administration. Beginning in 2008, students attended school Monday through Friday, and had a half-day every 1st, 3rd, and 5th (calendar permitting) Saturday of the month. Saturday lessons usually included Club Activity (CA) lessons, where students could participate in extracurricular activities. Unfortunately, many schools have regular classes without extracurricular activities because schools and parents want students to study more. Despite this, from 2012 onwards, primary and secondary schools, including middle schools, now do not hold Saturday classes. To this day, many schools still hold Saturday classes illegally because the parents want their children to go to school and study. In 1969, the government abolished entrance examinations for middle school students, replacing it with a system whereby primary school students within the same district are selected for middle schools by a lottery system. This has the effect of equalizing the quality of students from school to school, though schools in areas where students come from more privileged backgrounds still tend to outperform schools in poorer areas. Until recently, most middle schools have been same-sex, though in the past decade most