The key difference

Core tier: highest possible grade is C. Extended tier: highest possible grade is A*. Both tiers cover the same 21 topics, but Extended adds deeper "supplement" content and more challenging questions.

Choose Extended if

  • Your child is aiming for grades A*–B
  • They plan to study A-level Biology or sciences at A-level
  • They are comfortable with the subject and want to be challenged
  • Their school recommends Extended based on current performance

Choose Core if

  • Your child finds Biology consistently challenging
  • A solid C grade is the realistic target
  • They do not plan to study Biology beyond IGCSE
  • Reducing stress and ensuring a pass is the priority

Can you switch?

Yes: most schools allow tier changes up until the exam entry deadline (usually February of the exam year). Some schools make the decision later. If your child is struggling with Extended, dropping to Core ensures a fair chance at a C rather than risking a D or E on Extended.