The government-run school, flanked by a red dust road on the outskirts of Abuja, Nigeria, taught about 300 pupils who congregated from the surrounding rural area. But in March this year, the scruffy primary became part of a remarkable experiment. It was the first in Africa to get its hands on the so-called $100 laptop, a rugged device aimed at helping children in the developing world get the most from their education. The tough machines, conceived by the US-based One Laptop per Child (OLPC) group, were designed to replace dog-eared...