Teachers are unequally distributed across regions and income level of countries.

 Since 2000, pupil-teacher ratios have generally declined. The number of students in school from pre-primary to upper secondary has increased from 1.2 to 1.6 billion between 2000 to 2022 while the number of teachers has increased from about 55 million to 87 million. This excludes the additional 14 million teachers at the post-secondary level. Pupil-teacher ratios have declined for each level of education except for upper secondary which has more or less maintained a level of approximately 16 students per teacher (Figure 1). The largest drop has been at the preprimary level, declining from 20 to 14 students per teacher between 2000 and 2022.

Despite decreases in the pupil-teacher ratio, there are large disparities between regions and income categories of countries. For example, the global average pupil-teacher ratio was estimated to be 23 in 2022 (Table 1), but the difference between low- and high-income countries is substantial: low-income countries have more than twice the number of students per teacher, at 36, than high income countries, at 15.

 

Pupil-trained teacher ratios are much higher than pupil-teacher ratio due to the lower proportion of trained teachers in low-income countries.

The pupil-teacher ratio increases with respect to income level and tends to be higher in regions that have undergone relatively recent rapid expansion in enrollment in primary in the past decades, for instance, in sub-Saharan Africa. These disparities reflect the disparities in the quality of education. Extreme pupil-teacher ratios result in either significantly reduced class time through split shift instruction or in unmanageable classes with limited learning. Moderately high pupil-teacher ratios highlight the need for well qualified and trained teachers as having a larger number of students creates a more difficult environment to differentiate teaching to match student needs.