most of these studies. Since in most systems repetition implies just that repeating the
same material often with the same teacher without any special treatment and thus
repeating and experience that led to failure before this is perhaps not surprising if
discouraging. In many systems repeaters have a disproportionate tendency to drop out.
Paradoxically if repetition were reduced it might be expected to reduce average
achievement levels if it meant that larger proportions of lower ability children
proceeded to higher grades. Reducing repetition, where it is high (repetition rates in
Sub Saharan Africa are often 15% or more at primary level World Bank 1988:136) is
really a priority for other reasons. High repetition rates represent a serious source of
inefficiency which increases the unit costs of graduates from a particular cycle and fills
places with repeaters that might otherwise be occupied by those currently unenrolled.
Though average levels of achievement might deteriorate as a result of enrolling more
lower ability students, across the age group as whole (including those currently
unenrolled) achievement would rise and unit costs reduce.
It may be that within a wide band achievement is not related to class size, but this does
not mean there are no limits. Physical constraints (classroom size) and accepted
traditions place limits on what is acceptable. In most countries classrooms are not built
to accommodate more than about 50 students in comfort and class sizes in excess of
this result in overspill onto verandas without appropriate furniture. One of the highest
scoring IEA science study countries (Korea) has large class sizes averaging over 60.
But this is in a relatively well resourced system and one where learning motivation is
high and disciplined study part of the cultural heritage. Intuitively the significant factor
is when teaching practices change practical group work is difficult when class sizes
exceed 40, it may not be practiced below this number. A lecture is likely to be as
effective with 20 students as with 80 if the space is available. And class size probably
does interact with other variables - if textbooks/pupil are correlated with achievement,
large class sizes in situations where there is fixed stock of books (a realistic assumption
in a rapidly expanding system) will probably diminish the correlation.
Teachers' salaries, at the level of individual teachers, are unlikely to be directly related
to achievement for the simple reason that achievement is unlikely to be the result of the
teaching of a single teacher - students will experience several teachers over their careers
in school. Moreover it cannot lead to the conclusion that paying teachers better is
unlikely to have an effect on achievement - it may be that the most effective teachers do
not get the highest rewards; it may be that all teachers are paid so poorly that whatever
variation exists is not reflected in performance; it may also be that incomes are so low
they fail to provide motivation to all but the most dedicated. Given the fairly universal
belief that incomes should be related to effectiveness the challenge is to change the
reward structure so that they are.
The apparent ineffectiveness of level of laboratory provision may well reflect the nature
of science achievement tests. If these do not test the skills developed in laboratories