How Does a Teacher’s STEM College Major Affect the Academic Achievement of Their Students?

TANAKA Ryuichi
Faculty Fellow, RIETI

INOUE Atsushi
Nippon Institute for Research Advancement (NIRA)

Development of human capital in the science, technology, engineering and mathematics (STEM) fields

Enhancing science literacy is an important policy challenge, as it affects individuals' incomes and countries' economic growth. For example, the Strategy for Human Resources Development in the Science and Technology Fields, worked out in 2015 by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), mapped out the direction of policy for strategic development of high-added value STEM human capital and determined priority matters. In addition, the Ministry of Economy, Trade and Industry (METI), in cooperation with MEXT, established the Industry-Academia-Government Collaborative Roundtable on Human Resources Development in Science and Technology in 2015. The roundtable discussed three themes—"ways of matching higher education with industry's needs and enhancement of specialized education," "ways of promoting successful use of workers with a doctorate degree," and "expanding the base of STEM human capital and enhancing elementary and secondary education”—and worked out priority measures that should be taken from FY2016 onwards under the Action Plan for Collaborative Industry-Academia-Government Initiatives on Human Resources Development in Science and Technology (Ono, 2016).

Development of STEM human capital is related to the wage gap between men and women. For example, Card and Payne (2021) found that the gender difference in the probability of graduating with a STEM degree accounts for a fifth of the wage gap between men and women who have received higher education in the United States and Canada. In Japan, under the Fourth Basic Plan for Gender Equality, adopted in 2015, the Cabinet Office advocated the promotion of gender-equal opportunities in the fields of science, technology and academia and implemented various programs to train women to acquire STEM skills. This means that promoting STEM education is considered to be a policy measure that will improve labor productivity and correct the gender wage gap.

What Determines the Effectiveness of Teachers?

School education is one of the most important factors in terms of enhancing students' science literacy, and it goes without saying that teachers have an important role to play in providing education at school. However, according to various studies conducted both in Japan and overseas, there are significant disparities in the effect that teachers have on improving students' academic achievement. What determines the quality of teachers? On this question, previous studies based on empirical analysis have obtained varying results, with no sufficient consensus yet established. Even so, one attribute of teachers that has attracted researchers' attention is the level of teachers' professional expertise in the subject that they teach, and many studies indicated that improvement in students' academic achievement depends on this factor. However, few studies have reported on the mechanism through which the level of professional expertise in the subject taught may affect improvement in students' academic achievement. Our recent study (Inoue and Tanaka, 2022) focused on the college major of the teacher as an indicator of their professional expertise and examined the effect that the college major of science teachers may have on junior high school students' academic achievement and the mechanism through which this factor may affect academic achievement.

When examining the effects of teacher attributes on students' academic achievement, it is always necessary to keep in mind the fact that usually, pairings of teachers with students are not random. Even if a positive correlation is found between teachers with a degree in a certain college major and the level of students' academic achievement, that may not necessarily mean that teachers' professional expertise has positive effects. It may merely represent the tendency of teachers with a degree in that college major to be assigned to teach groups of competent students. In particular, when conducting an analysis using cross-section data (data from the same point in time) to look at disparities across students, it is difficult in many cases to distinguish the effects of teachers' attributes from the effects of other factors. Inoue and Tanaka (2022) resolved the above problem by looking at "within-student variations" across natural science fields (physics, chemistry, biology and earth science) and examined the effects of teachers' college majors on their students' academic achievement. The analysis used data concerning junior high school students from around the world obtained from an international academic achievement survey called the Trends in International Mathematics and Science Study (TIMSS).

Importance of science teachers' professional expertise

As a result of the analysis, it was found that learning under teachers with a natural science degree has the effect of improving students' academic achievement in the corresponding science subject by 0.05 points in terms of standard deviation (equivalent to 0.5 points in terms of deviation value) (Table 1). As for the mechanism that may underlie the positive effect, it was found that differences in teaching practices, particularly, preparation for classroom teaching, account for around half of the effect (Figure 1). In other words, the study indicated that learning under teachers with a natural science degree improves students' academic achievement as a result of the teachers' better preparation for classroom teaching in the corresponding science subject. The effects of teachers’ major on academic achievement varies depending on teachers' and students' attributes. For example, while the effect is larger when learning under teachers who majored in multiple fields, the number of teaching years, or having a master's or higher degree, does not increase the effect of the teachers’ majors. This finding indicates that the professional expertise level that is important for improving students' academic achievement is a bachelor's degree and that it is desirable for teachers to have extensive professional expertise in natural science fields. It also suggests that gaining more teaching experience does not necessarily make up for a lack of professional expertise. It was also confirmed that the effect of the teachers’ major is stronger in the case of female students and students with a high level of mathematics skills.

Similar results were obtained from another study by the author and his associate (Inoue and Tanaka, 2017), which focused on Japanese data. As a result of an analysis using data concerning public schools in Japan from TIMSS, it was confirmed that the test score level of eighth-grade students in science is higher by a statistically significant margin when the science teacher's college major is a natural science major than otherwise.

Need to train and retain teachers with a high level of professional expertise

From the abovementioned research results, it is clear that science teachers' college major is a factor that may improve students' academic achievement. From the policy perspective, it is worthwhile considering assigning science classes at junior high schools, such as physics, chemistry, biology and earth science, to teachers with professional expertise in relevant fields. If an arrangement like that is difficult, improving the quality of teaching practices, and particularly the preparation for classroom teaching, is expected to improve students' academic achievement. To that end, it is important to examine science teachers' level of professional expertise at each of the pre-recruitment training, recruiting, and post-recruitment training stages and to implement assistance measures to enhance their expertise as necessary.

Table 1. Effects of Teachers' College major on Students' Academic Achievement
Table 1.  Effects of Teachers' College major on Students' Academic Achievement
Notes: The regression includes student-teacher fixed effects and sub fields fixed effects (physics, chemistry, biology and earth science), and gives the same weight to earth country. Standard errors are clustered at class level and reported in parentheses. * p < 0.10; ** p < 0.05; *** p < 0.01.
Figure 1. Factors That Account for the Effects of Teachers' College Major on Students' Academic Achievement
Figure 1.  Factors That Account for the Effects of Teachers' College Major on Students' Academic Achievement
March 17, 2022

May 13, 2022