In advance of the new school year and in view of the ongoing discussions regarding large classes in Israel, the Taub Center is publishing a new study that examines the relationship between class size, instruction hours, and academic achievements from an international perspective. The study has found no significant statistical correlation between these variables. The study’s authors, Nachum Blass, Prof. Benjamin Bental, and Michael Debowy, suggest running a field test to see the effect on educational attainments of reducing class size while simultaneously reducing the number of instructional hours within the existing budgetary framework.
The education system budget, which is the second largest budget following defense and is composed primarily of teachers’ salaries, has a direct relationship to class size (which dictates the number of classes and the number of teachers) and the number of instructional hours per class. Every class is allocated an equal basic budget, between 29 and 32 hours, with additional hours allocated for each student over the 20th student. The majority of studies have shown that larger classes result in somewhat lower achievements, particularly among younger students and those from weaker socioeconomic backgrounds. Adding or subtracting instructional hours has a limited impact on academic achievements as well. That is, from a pedagogical perspective, there is some justification for reducing the number of students in a class and the number of teaching hour simultaneously. Taub Center researchers point to an option where the added costs of reducing the number of students in a class will be totally or partly eliminated by a reduction in the number of instructional hours per class . Reducing the number of instructional hours can balance the budget costs of lowering class size, and lowering class size can balance the “costs” of reducing instructional hours in terms of student achievements.
The Taub Center study examines the relationship between class size and instructional hours and academic achievements with the goal of determining if it is possible to reduce instructional hours while simultaneously reducing class size without harming student academic achievement thus eliminating the need for additional budget. To determine this, the study relied on results of the international TIMSS (primary school) and PISA (post-primary) exams for the years 1999–2019 as well as on data regarding class size and instruction hours in 31 countries participating in these international exams.
In a comparison of the relations between average class size and student scores in the various countries no clear relationship was found between the variables, largely because the differences between countries — in terms of class size and exam scores — were far greater than the changes within the countries over time. So, for example, in Japan and South Korea class sizes are large and test scores are high, whereas in Mexico and Israel, class sizes are large and exam scores are low. Similarly, there was no clear indication of a relationship between instructional hours and student achievement.
Ultimately, no statistically significant correlation between class size and instructional hours and student academic achievement was found. This finding indicates that it may be possible to reduce class size, with all of its accompanying educational advantages, without the heavy budgetary consequences of the increase in teacher instructional hours. Given the importance of this issue, the researchers stress, it would be worthwhile testing through a wide-spread field experiment.
The Taub Center for Social Policy Studies in Israel is an independent, non-partisan socioeconomic research institute. The Center provides decision makers and the public with research and findings on some of the most critical issues facing Israel in the areas of education, health, welfare, labor markets and economic policy in order to impact the decision-making process in Israel and to advance the well-being of all Israelis.