information:classification, linguistic:paraphrasing
Later education: 1942–1948

While Sâr was at the school, King Monivong died. In 1941, the French authorities appointed Norodom Sihanouk as his replacement. A new junior middle school, the Collége Pream Sihanouk, was established in Kampong Cham, and Sâr was selected as a boarder at the institution in 1942. This level of education afforded him a privileged position in Cambodian society. He learned to play the violin and took part in school plays. Much of his spare time was spent playing football (soccer) and basketball. Several fellow pupils, among them Hu Nim and Khieu Samphan, later served in his government. During the new year vacation in 1945, Sâr and several friends from his college theatre troupe went on a provincial tour in a bus to raise money for a trip to Angkor Wat. In 1947, he left the school.

That year, he passed exams that admitted him into the Lycée Sisowath, meanwhile living with Suong and his new wife. In summer 1948, he sat the brevet entry examinations for the upper classes of the Lycée, but failed. Unlike several of his friends, he could not continue on at the school for a baccalauréat. Instead, he enrolled in 1948 to study carpentry at the Ecole Technique in Russey Keo, in Phnom Penh's northern suburbs. This drop from an academic education to a vocational one likely came as a shock. His fellow students were generally of a lower class than those at the Lycée Sisowath, though they were not peasants. At the Ecole Technique, he met Ieng Sary, who became a close friend and later a member of his government. In summer 1949, Sâr passed his brevet and secured one of five scholarships allowing him to travel to France to study at one of its engineering schools.

During the Second World War, Nazi Germany invaded France, and in 1941 the Japanese ousted the French from Cambodia, with Sihanouk proclaiming his country's independence. After the war ended, France reasserted its control over Cambodia in 1946, but allowed for the creation of a new constitution and the establishment of various political parties. The most successful of these was the Democratic Party, which won the 1946 general election. According to historian David Chandler, Sâr and Sary worked for the party during its successful election campaign; conversely, Short maintains that Sâr had no contact with the party. Sihanouk opposed the party's left-leaning reforms and in 1948 dissolved the National Assembly, instead ruling by decree. The Việt Minh attempted to establish a nascent communist movement, but it was beset by ethnic tensions between the Khmer and Vietnamese. News of the group was censored from the press, and it is unlikely Sâr was aware of it.