An estimated 250 million children around the world cannot read, write, or demonstrate basic arithmetic skills.

Many of these children are in developing countries without regular access to quality schools or teachers.

The Global Learning XPrize is a challenge to teams around the world to develop software and apps for tablets that could help youngsters learn basic skills.

This week 11 semi-finalists were chosen from nearly 200 teams to move forward into the next stage of the competition.

Each team must create software that allows children to learn on their own.

BBC Click's Dan Simmons has been to one of the 150 villages in northern Tanzania selected to test the different tablet apps.