Chiwetel Ejiofor’s directorial debut, The Boy Who Harnessed the Wind, is this year’s British entry for Oscar’s recently renamed Best International Feature Film category. But the same rules apply: the film must be predominantly in a language other than English. In the case of Ejiofor’s film, that language is Chichewa, the local Bantu language of Malawi. It was a language Ejiofor didn’t speak and had to learn when he decided to take on a role in the film.

The true story follows William Kamkwamba (Maxwell Simba), a young schoolboy in Kasungu, Malawi, whose family struggles to pay for his schooling when a drought leads to a devastating famine and they are unable to farm the land. It’s his enterprising thirst for science—and a desire to teach himself even when he is refused a place at school—that leads him to design a windmill...