Instruction Time, Classroom Quality, and Academic Achievement

Many countries, American jurisdictions and charter schools have
recently embraced longer school days or more time devoted to core
academic classes. Recent research generally supports the notion that
additional time raises achievement, though difficulties isolating an
exogenous source of variation raise questions about the strength of
much of the evidence. Moreover, it seems likely that the magnitude
of any causal link between achievement and instruction time depends
upon the quality of instruction, the classroom environment, and the

This paper investigates the pattern of instruction time effects in
the 2009 Programme for International Student Assessment (PISA) data.

The empirical analysis shows that achievement increases with
instruction time and that the increase varies by both amount of
time and classroom environment. These results indicate that school
circumstances are important determinants of the likely benefits and
desirability of increased instruction time.