Double-shift or double-session schooling is a schooling system in which different cohorts of students
use the same building and have the same academic curriculum, some in the mornings and some
in the afternoons. Many developing countries, including Mexico, India, Brazil, Zimbabwe, Russia,
Bulgaria, have adopted the double-shift schooling system. In the United States, in states such as
Florida, a double-shift system is maintained due to the occurrence of natural disasters affecting the
physical conditions of existing school buildings. In general, the purpose of double-shift schooling is
to increase access to schooling while limiting strain on the budget.
From the policy perspective the introduction of double shifts allows existing sets of buildings
and facilities to serve more students. This may be especially important in urban areas, where
land is scarce and construction of new buildings is expensive. Double-shift schooling has helped
many countries to move toward universal primary and secondary education. However, this policy
may come at a cost. The limited school day under the multiple shift operation leaves few or no
opportunities for any extra-curricular activities. In addition, there is some concern that students
may be hurt by such policy. Afternoon students may receive a poorer education because of their
tiredness by the time of classes or the diminishing productivity of teachers. The purpose of this
study is to determine whether the difference in academic performance of students in the morning
and afternoon shifts has a causal nature or is due to differences in characteristics of students as a
result of the selection process.
Using a unique dataset from Mexico0
s National Institute for Educational Assessment and Evaluation
(INEE: Instituto Nacional para la Evaluaci´on de la Educaci´on ), I examine factors influencing
academic performance of students from different school shifts. More specifically, I focus on ninth
grade students of secondary schools from morning and afternoon shifts and examine the effects of
socio-economic and academic variables on students test score performance. To control for selection
bias I employ the Heckman two-stage model. My key identification for the selection equations comes
from exclusion restriction in which variable restricting school capacity determines the probability
of a student getting into the morning session but not their performance on the tests. Furthermore, I
apply the Oaxaca wage gap decomposition method to decompose the total effect into the effects of
observed characteristics, returns to characteristics, and selection. In addition, I extend the analysis
by decomposing the test difference due to observable characteristics into the three parts: due to the
student, teacher, and school characteristics.
The results of my study reveal that there is no causal effect of the morning shift on the academic
inequality of students from different shifts. Most of the test score difference can be explained by
differences in the characteristics of students. The results also suggest that half of the math test score
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gap is due to differences in the observed characteristics of teachers. The findings of my research
contribute an argument to the debate addressing the advantages and disadvantages of the doubleshift
schooling system. My results suggest that the double-shift schooling in Mexico serves its
purpose by providing the equal education opportunities to all students.