The whole process of raising and educating a child — instruction, correction, and discipline together. Hebrews 12 uses paideia to reframe suffering as God's fatherly training rather than punishment or abandonment.
Greek culture saw paideia as the formation of character through education and discipline. The NT adopts this: God's discipline is purposeful formation, not random hardship. No discipline seems pleasant at the time (Heb 12:11).
2 Timothy 3:16 identifies Scripture as the instrument of God's paideia — four overlapping functions all aimed at forming righteousness. The goal of all divine discipline is the character of Christ.