air-conditioned. In addition, an alumni database and electronic network was set up to facilitate communications between alumni worldwide. The school set up its website in March 1996, and the library acquired Internet connections. In February 1997, the offices of teachers and staff, the staff lounge and the exercise room were renovated and air-conditioned. The school launched a major expansion from 1997. The single-storey classrooms near David Chen Garden were demolished in June 1996. Replacing it were a four-storey building containing 24 classrooms, completed in October 1998. Similar arrangements were employed for the old classrooms on the other side of the school, of which the demolition works started in December 1998 and the new building was completed on late 1999. Formation of the Private and Butterworth sisters In 1961, Chung Ling (Private) High School was formed to take in those students who wished to receive their education totally in their mother tongue. In 1986, Chung Ling High School Butterworth Branch was opened. It was later renamed Chung Ling Butterworth High School to reflect its independent identity. Together with the Private School, the three Chung Lings became known as Tri-Chung Ling High Schools which share a Board of Governors but are essentially three independent schools. Changes in curriculum The Education Minister, his deputy and alumnus Michael Chen inspected the school on 8 April 1966, when the Minister announced that the school would commence pre-university course the next year. The course commenced 16 January 1967, enrolling 36 students, of which five were women. It was the first time that the school had enrolled women students. The school included extracurricular activities as one of the weighted subjects on 1 January 1989. Development The school celebrated its 50th anniversary on 25 August 1967, and held the third Annual Alumni Revisiting Day on the occasion. A diamond-jubilee celebration of the establishment of the school was held from 19–20 June 1992. The event concurred with the 10th Annual Alumni Revisiting Day. The school held two major events three years later. The first was the first Tri-Chung Ling High Schools Joint Sports Carnival, held on 15 August. On the same day, a memorial service was held in memoriam of the teachers and students died during the Second World War. Wang Yoong Nien retired as principal in December 1970. His position was occupied by Yeap Eng Hoe, who taught pre-university mathematics. Yeap Eng Hoe retired as principal on 14