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BECE, Vol.10, No.1, 2022 1337 

 

 

 

 

How do Class Size and Teacher’s Academic Quali-

fications Affect Students’ Academic Performance? 

An International Comparative study based on 

PISA 2018 Results 

By Yao, H., Hu, Y. Z., & Ma, L. C. 
Correspondence to: Hu, Y. Z., East China Normal University, China. E-mail: 

yzhu@dem.ecnu.edu.cn  

HE study, published in Tsinghua Journal of Education, uses PISA2018 

results of 15-year-old middle school students from four provincial ad-

ministrative regions in China (Beijing, Shanghai, Jiangsu, and Guangdong) , 

and other OECD countries as analysis sample to explore the differences in 

the distribution characteristics of class size and teacher academic qualifica-

tions between the four regions of China and OECD countries, and the impact 

of class size, teacher academic qualifications and their interaction terms on 

student academic performance. Multi-level linearity Model is adopted in the 

analysis. The results of the study are as follows. 

 There are remarkable differences in the distribution characteristics 

of class sizes and teacher academic qualifications in middle schools 

between China and OECD countries. Class size in China is relatively 

larger than that of OECD countries. In terms of teacher education 

qualifications, the proportion of teachers with a master’s degree in 

OECD countries is higher than China. In terms of the distribution of 

teacher academic qualifications corresponding to different class siz-

es, the distribution curve of class sizes and teachers’ academic quali-

fications in OECD countries follows the rule of large classes with 

low teacher academic qualifications and small classes with high 

teacher academic qualifications, while the distribution curve in the 

four regions in China presents irregular wave patterns. 

 Reducing class size and upgrading teacher academic qualifications 

will help improve student performance. When the class size of the 

four regions in China is reduced from more than 50 students to 41-

45 students and 46-50 students, the improvement in student academ-

ic performance is significant; When the class size in OECD coun-

tries is reduced from more than 50 students to 16-20 students, or 26-

30 students, or 31-35 students, students can improve their perfor-

mance effectively. In terms of the impact of teachers’ academic 

T 

mailto:yzhu@dem.ecnu.edu.cn


 

BECE, Vol.10, No.1, 2022 1338 

qualifications on student performance, every 10% increase in the 

proportion of the master’s degree in the faculty will result in an av-

erage increase of 10.2 points in mathematics scores for students in 

the four regions of China, and an average increase of 5.6 points for 

students in OECD countries. 

 A quadratic test of class size in OECD countries indicates that class 

size has a non-linear relationship with the improvement of student 

academic performance, and the best marginal benefit range for 

measuring the impact of class size on student performance is 21-30 

students per class. 

 The interaction between class size and teacher academic qualifica-

tions is tested, and it is found that class size and teacher academic 

qualifications have a “mutually independent” effect on student aca-

demic performance in China, while in OECD countries, they have a 

“mutually substituting” effect on student academic performance. 

Both have their own specific role thresholds. 

The research results indicate that the benefits of reducing class size 

and upgrading teachers’ academic qualifications are not only reflected in stu-

dent performance improvement, but also in the development of students’ 

non-cognitive abilities. Reducing class size helps to regulate student behavior 

and enhance students’ emotional skills. Upgrading teacher academic qualifi-

cations can also promote pertinent instructions according to students’ peculi-

arities and guide individual students to achieve distinctive and diversified 

development. These benefits beyond academic achievements deserve further 

studying. 

In benchmarking the relevant indicators of OECD countries to pro-

mote the development of education in China, it is necessary to consider Chi-

na’s economic development level as a upper-middle-income country, the 

scarcity of high-quality educational resources and the unbalanced develop-

ment of education at the current stage. Under the principle of steady change 

and gradual advancement, empirical models based on large sample data 

should be built to measure the marginal costs and marginal benefits of differ-

ent programs to formulate a more scientific and efficient strategy for the 

high-quality development of compulsory education. 

 

Source: Tsinghua Journal of Education, 2021(5):40-54.

 

 

 

 

 

 

 
 

 


