What marks measure, and what they miss

A school report is the densest piece of information a family has about a child's mind, and for most families it is the only piece. It is therefore asked to answer questions it was never built to answer — whether the child is suited to engineering, whether they should take commerce, whether they are, in the phrase everyone uses, a bright child.

What a mark is actually a record of

A mark records performance on a defined syllabus, assessed in a particular format, at a particular time, under examination conditions. Each of those qualifiers removes something.

The syllabus limits it: a student is being measured on the material selected for measurement, which is a small and deliberate slice of any subject. The format limits it: written recall under time pressure rewards a specific combination of memory, speed and composure. The occasion limits it: one bad fortnight is not distinguishable, in the number, from a year of not understanding.

What it conflates

The larger problem is that a single mark is a sum of several different things that a decision would need to hold apart. A mark of 64 in mathematics may reflect weak reasoning with the material, or strong reasoning with insufficient practice, or good understanding poorly expressed under time, or an excellent grasp of four topics and none at all of the fifth. Those are four different students requiring four different responses, and the number is identical for all of them.

Marks are an outcome. A career decision needs the inputs, and the outcome does not decompose back into them.

Where marks and aptitude diverge

Marks and measured aptitude often agree, which is why the divergences are informative. A student with marked reasoning ability and mediocre marks is telling you something — about method, about motivation, about conditions at home, about the fit between them and the way the subject is being taught. A student with modest measured aptitude and consistently strong marks is also telling you something, usually about work, method and persistence, which are not lesser qualities.

Neither pattern is a reason to overrule the other. Both are a reason to ask a question that the marks alone would not have raised.

What marks do well

They should not be dismissed, and the case against over-reading them is not a case for ignoring them. Marks accumulated over years, across subjects, from many different assessors, are a substantial body of evidence about how a student performs in a real institution over a long period. That is more than any single sitting of any instrument can offer. Their strength is duration and volume; their weakness is that they do not separate their own ingredients.

Using them properly

The workable position is to treat marks as one source among several, to read the pattern across subjects rather than the aggregate, to attend to the trend more than the level, and to treat any sharp divergence between marks and other evidence as a question rather than a contradiction. A subject where the mark has been falling for three terms is more informative than a subject with a low but flat mark, and the aggregate percentage hides both.