The 5th Primary School of Aretsou, Derkon, Kouri, and Katirli. End-of-School-Year Performances in the Schoolyard in 1969

Rysio, through the efforts of teachers Philippos Kargopoulos and Stylianos Tzormpatzikostis, quickly acquired a school at the site of today's 5th Primary School. During the Interwar period, it was known as "RKK"—Rysio, Kouri, and Katirli.

The school was founded on October 15, 1926, with construction costs amounting to 150,000 drachmas, and it began operating at the end of 1927. Its first headmaster was Philippos Kargopoulos, while Christos Asproulis served as the chairman of the school committee. The supervisory committee, consisting of K. Arampoglou, Ath. Roditis, G. Mavrogelastos, and Christos Asproulis (chairman), showed great dedication and commitment in completing the project.

From the 1928–1929 academic year onwards, various fundraising events were organized to support the school, including school theater performances and raffles featuring handcrafted items made by the students (Makedonia, June 15, 1929).

Before the construction of the school in Rysio, students had to attend school in Kalamaria. By 1932–1933, the settlement's population was approximately 800 residents. According to student records categorized by "father's occupation," Aretsou had the greatest variety of professions among all the coastal settlements. However, it had very few commercial establishments—only two bakeries, two barber shops, and four cafés.