Between 2021 and 2025, AI-enabled teaching emerged as a key innovation in addressing global educational challenges such as teacher shortages, learning disparities, and skills gaps. For the first time, it promised to give learners outside of a lab or limited settings, a personal teacher available to support their diverse needs in highly personalised ways 24/7. This paper critically reviews the evolution of AI-integrated teaching, synthesising insights from existing literature alongside findings from four major research studies conducted by the authors during this period. Central to these investigations is OIAI, an AI-teacher system developed and piloted by the researchers across Africa, Europe, Asia, North America and South America. These form the basis of a pioneering implementation in two African nations; Kenya and São Tomé and Príncipe, in 2025.