Most people in sub-Saharan Africa may not have a computer, but 60% of them (and rising) have phones: and Sterio.me is using them to empower African education systems.

According to UNESCO, OECD countries average one teacher for every 21 students. In Rwanda, there's 65 students to a teacher, and in the Central African Republic there's 84. Worse still, some areas suffer from a lack of teacher training and the quality of education is poor.

That's why Sterio.me aims to help students learn from outside of the classroom. All they have to do is send an SMS message from their mobile, and they'll receive a free call back with an audio lesson or quiz. Teachers can choose the material their students access, record quizzes, and track results to monitor progress. And it's all on a standard mobile - no smartphone necessary.

Sterio.me has partnered with Vodacom to launch in Lesotho this month, where they will be looking to showcase the potential of their product with a view to selling to non-profits.

Similar models have been adopted by startups like Kenya's Enzo Education, which charges 30 cents per month for access to content, but the innovative potential of Sterio.me's flexible content creation element and their courting of non-profit Goliaths to fuel a spread across the continent gives them a powerful edge.