Season of Birth and School Success in the Early Years of
Primary Education – P. Verachtert, B. De Fraine, P.
Onghena & P. Ghesquière
There is a clear relationship between students’ season of birth and their success in school. Older
children generally outperform younger children within the same year. These younger ones are at an
increased risk of being incorrectly identified as having learning difficulties. The effects diminish as
children grow older and is visible in both education and sports.
The season of birth effect on education is primarily explained by the age position effect, where
younger children in a class are at a developmental disadvantage compared to older peers, leading to
lower academic performance. Other explanations, such as medical factors and differences in the
length of schooling are less supported by research.
Flanders has high retention rates, in contrast to the UK, complicating the relationship between birth
season and school success, and little research has been conducted here. A caveat regarding the effect
is that it doesn’t solely depend on the birth month itself, but also on factors such as the education
system, age of entry and individual differences.
Questions:
1. Can we find a relationship between season of birth and grade retention?
Yes, children born later in the year (younger within their grade cohort) are more
likely to be held back a grade compared to their older peers born earlier in the year.
2. Do the relatively large age differences between children within the same cohort result in
different levels of mathematical abilities at the start of first grade?
Yes, younger children (born later in the year) generally start first grade with lower
math achievement compared to their older classmates.
3. How do these age-related achievement differences evolve between the start of first grade
and the end of second grade?
The achievement gap between younger and older children narrows slightly over the
first two years of school, but it remains significant by the end of second grade.
4. Does this achievement gap develop differently in classrooms with frequent differentiated
instruction practices than in classrooms where there is less attention for children’s individual
learning needs?
No. This indicates that current differentiation practices may not be sufficient to
address the gap related to birth season.
Schools should be careful with grade retention, revise current differentiation methods and teachers
must be aware of the season of birth effect.
Primary Education – P. Verachtert, B. De Fraine, P.
Onghena & P. Ghesquière
There is a clear relationship between students’ season of birth and their success in school. Older
children generally outperform younger children within the same year. These younger ones are at an
increased risk of being incorrectly identified as having learning difficulties. The effects diminish as
children grow older and is visible in both education and sports.
The season of birth effect on education is primarily explained by the age position effect, where
younger children in a class are at a developmental disadvantage compared to older peers, leading to
lower academic performance. Other explanations, such as medical factors and differences in the
length of schooling are less supported by research.
Flanders has high retention rates, in contrast to the UK, complicating the relationship between birth
season and school success, and little research has been conducted here. A caveat regarding the effect
is that it doesn’t solely depend on the birth month itself, but also on factors such as the education
system, age of entry and individual differences.
Questions:
1. Can we find a relationship between season of birth and grade retention?
Yes, children born later in the year (younger within their grade cohort) are more
likely to be held back a grade compared to their older peers born earlier in the year.
2. Do the relatively large age differences between children within the same cohort result in
different levels of mathematical abilities at the start of first grade?
Yes, younger children (born later in the year) generally start first grade with lower
math achievement compared to their older classmates.
3. How do these age-related achievement differences evolve between the start of first grade
and the end of second grade?
The achievement gap between younger and older children narrows slightly over the
first two years of school, but it remains significant by the end of second grade.
4. Does this achievement gap develop differently in classrooms with frequent differentiated
instruction practices than in classrooms where there is less attention for children’s individual
learning needs?
No. This indicates that current differentiation practices may not be sufficient to
address the gap related to birth season.
Schools should be careful with grade retention, revise current differentiation methods and teachers
must be aware of the season of birth effect.
