The Ministry of Education (MOE) told the media on Monday afternoon that flags at MOE schools flew at half-mast from the morning, as a mark of respect to the late Mr Lee Kuan Yew after he died at 3.18am.
He died at the Singapore General Hospital where he had been warded for severe pneumonia since Feb 5.
Schools also observed a minute's silence during Monday morning's assembly.
On Tuesday, school leaders will address students and staff during assembly and reflect on Mr Lee's life and legacy.
School leaders will refer to Education Minister Heng Swee Keat's message to the MOE community.
Teachers, staff and students from Government schools and post-secondary educational institutions (PSEIs), and MOE headquarters staff will participate in state events such as the Lying-in-State, Special Parliament Sitting and the State Funeral Service.