Born in 1930 to a recently widowed Englishwoman on a homestead in rural Natal, little Peter Philip (Guy Witcher) is schooled in the ways of England by his mother and the ways of Africa by a Zulu nanny (Nomadlozi Kubheka), whose son Tonderai is also his best friend. Their easy life is forever shattered, however, when the farm's cattle are claimed by rinderpest. PK's mother succumbs to a nervous breakdown, and he is sent away to a conservative Afrikaans boarding school while she recovers.
Being the only English speaker, PK soon earns almost universal contempt from his scathing Afrikaner fellows—particularly an older student, Jaapie Botha. Botha's abuse and the inferiority complex which results strikes PK with a severe case of nocturnal enuresis, a habit which he eventually overcomes with local sangoma Dabula Manzi. In conquering his nightmares, PK is given a chicken (Mother Courage), which becomes his closest companion. Botha subsequently captures PK and Mother Courage and has them tried before a mock court while elaborating on the depth of his hatred for the British—a people he holds responsible for atrocities committed during the Second Boer War. The Afrikaans boys hang Mother Courage and kill her with a rock, but their attempts to kill PK in a similar manner are interrupted by a teacher who later oversees Botha's expulsion.
With his mother dead, PK finds himself living with his grandfather in Barberton. He eventually seeks a mentor in Karl "Doc" von Vollensteen (Armin Mueller-Stahl), a lonely German musician who lost his family in Europe. Doc warms to PK and under his guidance the latter soon becomes an excellent pianist. He is interned as an enemy alien at the onset of World War II, but PK continues to visit him regularly in prison. Doc introduces the boy to Geel Piet, a Cape Coloured inmate who takes von Vollensteen's place as PK's mentor, training him to be an excellent boxer. Piet also impresses on PK his mantra: "first with the head, then with the heart", a phrase that will see the young man through even greater hard times ahead.
A maturing PK (Simon Fenton) begins to express sympathy towards black prisoners, who are detained under appalling conditions. He works with Doc to distribute contraband among the Africans, writing their letters to home, and sharing their many sufferings. The war does not end happily for PK, as Doc is repatriated and Piet—seriously injured by a white warder—fails to survive his sentence. PK is sent away again, this time to study at the prestigious Prince of Wales School in Johannesburg. While attending a boxing championship, he is enamoured by Maria Marais, daughter of a leading National Party official. Since her strict father will not permit them to see each other openly, they begin dating in secret. On one such outing they are introduced to Gideon Duma, a prominent boxer in Alexandra, a notorious black township. Duma's passion for resisting apartheid inspires PK, and he begins teaching English at a rural African school.
Maria's father, incensed by the couple's ongoing relationship and PK's ties to a multiracial gym, leads him to request a formal investigation by one of his South African Police contacts, Colonel Breyten. Breyten and his sergeant, an embittered Jaapie Botha, place PK under surveillance for subversion. His clashes with the SAP finally come to a head when Maria is killed during a raid on a biracial church by the security forces. Maddened by grief, PK considers fleeing to England, but is consoled by his former boxing partner, who reminds him of all the good he can still do in Africa.
Botha leads a violent raid on Alexandra the following night. He threatens to shoot Elias Mlungisi, the local boxing promoter, only to be confronted by PK. They spar; PK easily bests his childhood enemy. Botha is still bent on executing the erstwhile victor, but an arriving Gideon Duma despatches the policeman with a cricket bat before he can fire. Now fugitives from the apartheid government, PK and Duma vow to continue a campaign against racial injustice. Peter's closing narration identifies meaningful voices during his life; from mother and nanny, to Doc and Dabula Manzi, Geel Piet and, finally, Maria Marais.

Question: What does Doc teach Peter?
Answer: to play the piano