IB is unashamedly a pre-university course aimed at highly motivated secondary school students. Around 50 institutions in the UK have opted for it, half of them state schools.
Holistic principles lie at the heart of the IB: its broad curriculum requires candidates to cover humanities, arts and sciences in six academic subjects, with an emphasis on making links between disciplines. The IB also values the student's first language and culture.
What does this holistic approach mean in terms of exams and assessments? Sandra Morton, sixth form director at Impington Village College in Cambridgeshire, an IB enthusiast, points first to the Diploma's "Creativity, Action and Service" (CAS) element. "The student has to do a minimum of 150 hours of CAS," she says. "The IB places a lot of emphasis on the service element. It might be working in an Oxfam shop, or helping a disabled adult with making course notes, or mentoring younger pupils."
The student tracks and records the time spent on CAS, and schools use various reporting methods - a portfolio, a diary, a written overview. What isn't acceptable, Sandra Morton says, is just to go through the motions.
"Every year, diplomas are withheld because this element is unsatisfactory."
The thrust of the assessment process is to confirm that the student has an independent and mature attitude to life and learning.
"The aim always is that students will see subjects in a broader context - what does it mean when a mathematician knows something? How is it different from knowing something in history or art? It forces them to think at a highly critical level - to see that being a historian entails knowing more than the facts of history."
This quest for a broad understanding is seen in the 4,000-word extended essay that every student has to complete on a topic of special interest. It also lies behind the compulsory "Theory of Knowledge" (TOK) course, intended "to stimulate critical reflection on the knowledge and experience gained inside and outside the classroom".
There is an emphasis on oral exams and presentations to supplement course work and exams. The TOK component, for example, calls for an oral presentation that carries one-third of the assessment. As well as an oral exam in languages, which you would expect, examiners in creative subjects such as dance and art will discuss work with the students.
This search for links and broader judgements extends into science, where a student of, say, physics, has to work on a group project in another scientific discipline. All in all, Sandra Morton says: "Even though the IB has been in existence for 35 years, the assessment procedures are more radical than the newer AS and A2 system. All subjects have a coursework component and there's absolutely a greater emphasis on oral and presentation skills."
All of this, she believes, means that the IB prepares students for higher education more effectively than does the A-level programme. "The student has to show the ability to research independently, and to present work orally and in writing, and with a high level of academic sophistication," she says, "It moves them on to be independent learners."
That's a phrase, she suggests, that is sometimes used glibly. "Many students leaving school are not independent learners, but they need those skills if they're to survive and thrive. The IB is excellent preparation for university."