Statistic of the Month: Teachers’ Salaries, Class Size and Teaching Time

By Jennifer Craw

This year’s edition of the OECD’s annual report Education at a Glance offers new insight into what factors influence how education systems invest in teachers. This data looks at how each country spends the money that it dedicates to paying teachers by analyzing four factors that contribute to that cost: 1) level of teacher salary; 2) required amount of time students spend in school (instructional time); 3) teaching time, or how much time teachers devote to directly teaching students rather than related activities like planning or meeting with other teachers; and 4) class size.   OECD looks at the cost of teacher salary per student, but then isolates the effect of each of these factors on the overall cost.

The chart below shows the OECD’s calculation for teachers’ salaries per student in lower secondary schools in OECD member countries. The United States is highlighted in red and top performing countries on PISA appear in dark blue. A few top performing systems – Hong Kong, Shanghai, Singapore and Taiwan – are not included in Education at a Glance since they are not OECD member nations.

Cost of teacher salary

According to the this chart, the U.S. falls near the middle of the pack for overall teacher salary per student, and top performers like Netherlands, Australia and Finland are near the top.

When the OECD analyzed the effect of each of the four contributing factors, level of salary for individual teachers has the most impact on cost. This is no surprise; it is also a finding that is hard to analyze since absolute salary levels are hard to compare among countries with very different costs of living and distributions of salaries across their economies. OECD also found that instructional time had the least effect in most countries. Of greater interest, and what we discuss below, is the effect of class size and teaching time on overall teaching cost compared across OECD countries.

The next chart shows the effect of class size on the cost of teachers’ salaries per pupil. A country that hires more teachers to reduce class size will spend more money on teachers’ salaries to do so, no matter what teachers are paid.

Cost of class size

In this chart, the negative numbers represent countries that are spending less on teachers’ salaries by allowing larger than average class sizes, while the positive numbers represent countries that spend more money on teachers’ salaries by reducing class sizes. The top performers are spread out along the spectrum, with Korea at the low end, where larger class size has the effect of making the cost of teachers’ salaries per student lower for the system, while Finland is toward the upper end, with the cost of smaller than average class sizes increasing the cost of teachers’ salaries per student. The United States is among those countries with smaller than average class sizes which increase the cost per student. The OECD finds that class size has the second greatest impact on overall teacher costs, after teacher salaries.

The number of hours teachers spend directly teaching students rather than preparing lessons, meeting with parents, observing or meeting with other teachers, also plays into this equation. Some countries require teachers to teach many more hours than others, and this impacts the number of teachers that need to be hired. The next chart explores the impact of required teaching time on the cost of teachers’ salaries per student.

Cost of Teaching Time
The countries with teacher pay per student reduced (in the negative dollars) are countries where teaching time is greater than the OECD average of 691 hours per year and fewer teachers are needed. The countries with positive dollar amounts are those that require less than the average teaching time and therefore spend more money on teacher salary per student because more teachers are needed per student. This chart highlights most strikingly the differences between how the United States spends money on teachers and how top performers spend money on teachers. The United States spends less on teachers’ salaries per student by expecting its teachers to spend more time directly in front of students. Meanwhile, top performers like Japan, Estonia, Poland, Korea and Finland all spend money to ensure that teachers have time outside of teaching to continuously improve their craft. Shanghai, China and Hong Kong, jurisdictions which are not included in Education at a Glance, also require teachers to teach only a fraction of the time of U.S. teachers. Teachers use the time when they are not teaching to work with peers on improving lessons, observe other teachers, conduct research, and many other important activities that contribute to the high performance of their students.

Taken together, the data shows that when it comes to deciding how to spend money on teachers, the United States spends more money to reduce class size and less money by increasing the teaching time of its teachers. Meanwhile, the top performing countries are more likely to spend money that provides time for teachers to continuously develop their knowledge and skills, and they are not as concerned with maintaining small classes. It is a policy tradeoff that the United States should consider. For NCEE’s take on how the United States can better support its teaching force and better spend the money it does on teachers, see the recent report, Fixing Our National Accountability System.