"Interactive Radio Instruction (IRI) is the use of interactive lessons delivered through either radio broadcast or audiocassette. An "audio" teacher directs the lessons while classroom teachers serve as facilitators. IRI has been used in developing countries worldwide to improve the quality of education across a range of school subjects and to serve as a form of teacher development. Multiple studies of IRI consistently have shown high learning gains, decreased equity gaps, and cost-effectiveness. Twenty-three years after their initial launch, several major IRI projects continue to operate successfully. While over the years IRI has been updated in various ways, its basic structure and methodology remain largely unaltered. IRI continues to be used in projects around the world." (Abstract)