It is conclusively presumed that a child under 10 cannot commit a criminal offence (s 344 CYF Act).
For young people under 14 to be found guilty of a criminal offence, the prosecution must prove they were aware of the serious wrongfulness of their action (R (a child) v Whitty  66 A Crim R 462). For a child of normal intelligence, proof of commission of a significantly serious act may of itself be enough to discharge the onus (R v ALH  VSCA 129).
A child over the age of 14 is regarded as having the same knowledge of wrongfulness as an adult, and ignorance of the law is not an excuse for any offence. Unless charged with killing someone, a person under 18 at the time of the alleged commission of the offence, and who is still under 19 when the case goes to court, will go to a Children’s Court. (See The Children’s Court. See also sections relating to children in Arrest, search, interrogation and your rights.)