In the Association of Southeast Asian Nations (ASEAN) region, there is a learning crisis. Children from the most marginalised groups face insurmountable barriers to accessing a quality education, while many of those who are in school are not learning. Foundational learning is often described as the essential skills and knowledge that serve as the basis for further learning and development, and includes basic literacy (reading and writing) and numeracy (mathematics), and more recently, a focus on critical thinking, problem-solving, and socioemotional skills. In collaboration, ASEAN and the United Kingdom have established the Supporting the Advancement of Girls' Education (SAGE) Programme under their ASEAN-UK partnership. This initiative is designed to narrow the development gap between the first six ASEAN members and the four newer member countries (Cambodia, Myanmar, Lao PDR and Viet Nam) and Timor-Leste, by addressing their education priorities within the ASEAN region, specifically focusing on challenges faced by girls and marginalised groups. The SAGE program aims to understand early-grade students' challenges in the ASEAN region, identify effective practices to address these issues and provide practical recommendations to empower students with essential foundational skills for lifelong learning. This report, part of a three-part series, focuses on supporting foundational learning in primary school settings in ASEAN countries. Its objective is to comprehend the challenges faced by the region in promoting foundational learning.