Boundaries are set after each series, once the exam board can see how the cohort performed on that particular set of papers. A harder paper produces lower boundaries; an easier one raises them. That is the mechanism designed to keep a grade meaning the same thing year to year.
What this means in practice
- A past paper score should be compared against that paper's own published boundaries, not a fixed percentage.
- Boundaries from a single year are a poor target; look at the range across several years.
- Aim comfortably above the boundary you want, because you cannot know in advance which way the paper will fall.
How to use boundaries when revising
- Work out the marks between your current score and your target boundary.
- Look at where those marks were lost, by topic and by error type.
- Convert that into a revision list; a target grade becomes a concrete set of questions to fix.
Expressed that way, a grade jump usually turns out to be a small number of recurring errors rather than a general shortfall in ability.