Internal Assessments (IA) for the International Baccalaureate (IB)

Q: What does Internal Assessments (IA) for the International Baccalaureate (IB) cover?
A: A clear, parent- and student-friendly roadmap to the 2025 IB Internal Assessment: mark-scheme anatomy, STEM-savvy topic hacks.

TL;DR
Each IB Diploma subject includes an internally assessed component that is teacher-marked and externally moderated. The exact weighting, criteria and length guidance are subject-specific, so treat the latest subject guide issued by your school as the source of truth. Start early, keep your data/uncertainty handling tight, and align every section of your report to the published criteria.

Status: IB assessment principles + academic integrity policy checked 2026-01-26. Subject-guide specifics (weightings, criteria, and recommended length) vary by subject and can change-confirm against the latest guide provided by your school.

1 | What the IA Is -and Why Integrated Programme (IP) students Should Care

• Mini-thesis inside the diploma. One individually written investigation per subject, marked by the teacher, then moderated by the IB (confirm the exact weighting and rules in your subject guide).
• Tight frame. Subject guides emphasise clear, concise communication so moderators can read efficiently (follow your school’s most recent guidance on length and structure).
• Planned time in the scheme of work. Schools typically allocate in-class time for planning, execution and write-up-treat that as the minimum and plan extra buffer at home.
• Skill overlap with IP Weighted Assessments (WAs). Planning, LINEST gradients, ± SE quoting and ACE-style evaluation mirror the A-Level H2 Paper 4 rubric your Y5-6 IP students will meet.
• University hook. Selective STEM degrees (e.g. Cambridge Natural Sciences, Imperial Engineering) invite IA/EE titles in supplementary questionnaires, so a Math-Physics crossover project signals depth early.

2 | Mark-Scheme Anatomy (Physics / Maths)