The rulebook at School 24 gives one page to attendance, and the whole page turns on two words.
«To sit the end-of-year examination, a pupil must attend at least 85 percent of the year's lessons.» There are 120 lessons in the year, so the rule asks for 102 of them. A pupil who attends exactly 102 has met it — at least includes the number itself, and the registrar is careful to say so when parents telephone.
Read from the other end, the same rule says something friendlier: a pupil may miss no more than 18 lessons. Both sentences draw the same line in the same place; one counts what you have, the other counts what you have spent.
Two cases from last year show how narrow that line is. A pupil who missed 15 lessons attended 105, comfortably above the threshold, and sat the paper. A pupil who missed 19 attended 101 — one lesson short — and did not. She appealed, and the appeal was refused, because a rule that bends for one lesson has no edge at all.
The registrar's advice to every new class is not about mathematics. Do not aim for the boundary, he says. Aim well inside it, because flu does not consult the rulebook, and neither does a delayed bus.