DAR ES SALAAM, June 17 -- Few national investments shape a countrys future more profoundly than education. Tanzania has recognised this reality for decades, expanding access to schooling, investing in classrooms and teachers, and ensuring that millions more children have the opportunity to learn.

Yet as education systems around the world are discovering, access alone is no longer enough. The next challenge is ensuring that children acquire the foundational skills they need early enough to succeed throughout their lives.

A child may spend the day in school, complete assignments and move from one grade to the next, yet still struggle to read with understanding. The lesson may have been taught, but learning does not always happen the first...