Ten years ago I was 19 and traveling through East Africa, and I spent a summer in Ibumila, a village in the Njombe highlands of Tanzania. There's no school in the village. The nearest one is a boarding school an hour away that costs a few hundred dollars a year, which is out of reach for most families there and was about two weeks of summer job money for me. The daughter of the family I stayed with, Anwarite, was 11. I offered to pay her fees and told myself I'd keep paying as long as she wanted...