Media Briefings

INSTRUCTION TIME AND CLASSROOM QUALITY: The effects on teenagers’ school performance

  • Published Date: November 2015

Teenagers can get better results from additional hours in school – but only if they are in a classroom environment that is conducive to learning. What’s more, the benefits of extra instruction time in mathematics and languages decline as classes get longer.

These are the main findings of research by Steven Rivkin and Jeffrey Schiman, published in the November 2015 issue of the Economic Journal. Their study analyses data from the 2009 Programme for International Student Assessment (PISA), a survey and assessment administered to 15-year-old school students around the world.

The researchers estimate the average benefit of additional instruction time as well as variation in this benefit relative to the quality of the classroom environment. Their empirical analysis shows that more time devoted to mathematics and language arts instruction raises achievement in these subjects unless the classroom environment is not conducive to learning.

In addition, the evidence suggests that the benefits of additional time decline as the length of classes increase. This may be due to fatigue on the part of the students or a diminishing benefit of additional material.

The belief that additional time increases learning and achievement seems uncontroversial, the authors note. But if instruction is of poor quality or the classroom is beset by disruption, the additional time may yield little or no return.

Until recently, there was little compelling evidence on the benefits of additional instruction time, because it is difficult to separate its effects from other factors. More academically oriented children in higher wealth schools tend to spend more time studying the core academic subjects, but their generally higher levels of achievement probably come from many factors of which more instruction time is only one.

The availability of assessments and information on instruction time in both mathematics and language arts enables the contribution of instruction time to be separated from other factors. The finding that children in schools where relatively more time is devoted to mathematics tend to score higher in mathematics relative to reading provides compelling evidence that additional instruction time contributes to learning.

Importantly, the PISA data also enable the measurement of classroom environments on the basis of responses to questions about student behaviour and student-teacher interactions. The estimates indicate that a better classroom environment increases the benefits of additional instructional time.

There is a widely held belief that additional time devoted to mathematics or language arts instruction increases achievement in these subjects. A number of countries and local education authorities have implemented policies that increase the length of the school day or year or hours committed to academics. Many charter schools serving disadvantaged students in the United States, including those adhering to a ‘no excuses’ philosophy, ascribe to this view and devote more time to these subjects.

The authors of this new research respond:

‘Our analysis strongly suggests that more instructional time does not substitute for a poor classroom environment or low-quality instruction.’

‘Rather the benefits of additional time depend on the efforts of the school to establish an effective learning environment.’


Notes for editors: ‘Instruction Time, Classroom Quality, and Academic Achievement’ by Steven Rivkin and Jeffrey Schiman is published in the November 2015 issue of the Economic Journal.

Steven Rivkin and Jeffrey Schiman are at the University of Illinois at Chicago.

For further information: contact Romesh Vaitilingam on +44-7768-661095 (email:; Twitter: @econromesh) or Steven Rivkin on email: