1971 marks the beginning of form 6 classes, with an enrolment of 37 students. Further additions were made to the school in 1973. A 3-storey science block was constructed. The building was named after Ng Song Teik, the brother of Dato’ Ng Song Choon. The ground floor of the building comprises the school canteen. The building was opened by the Yang Berhormat Haji Mohamed bin Yaacob, Minister of Education, on 11 May 1974. In 1976, SMJK Sam Tet celebrated its 25th anniversary. The occasion was officiated by Chan Siang Sun J.P., J.S.M., Deputy Minister of Education.