B3 · Higher Level

Object-oriented programming

Organize larger programs around clear responsibilities and interacting objects.

DP1 · April–May 2027; HL depth in DP2 · proposed

Learning goals

  • Design classes with appropriate state and behaviour.
  • Implement and test interactions between objects.
  • Develop inheritance and polymorphism in the HL continuation.

In practice

  1. Refactor a procedural program into cooperating classes.
  2. Use persistent data in an integrated application.
  3. Review another design and justify an alternative.

Show understanding

A working multi-class program and a reasoned account of design choices.

Predict first. Implement second. Test deliberately. Explain what the evidence shows.