The fourth chapter of the Khuddaka-Pātha (Khp.2).
It consists of ten questions which, according to the Commentaries (KhpA.76; ThagA.i.479), the Buddha asked the young Sopāka, then an arahant though only seven years old, with the idea of giving him the upasampadā-ordination.
The boy-arahant answered the questions and this conversation formed his ordination. (See also Thag.v.485; Ap.i.64f).
These questions were elaborated by the nun of Kajangalā (see A.v.54ff). (q.v.).
The Majjhima Commentary (MA.ii.636) on the Ambalatthika-Rāhulovāda Sutta seems to indicate a set of questions called Kumārapañha in connection with Rāhula when he was seven years old.
See also SA.iii.99, where Buddhaghosa says that Cittagahapati, in a discussion with Nigantha Nātaputta, referred to the Kumārapañha.