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Birthdate and student achievement: The effects of school grouping practices in British Columbia

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Mussio, Jerry & McCrea, Pat
Publication Date: 
7 Jun 2011

Excerpts from the report:

In recent years, a number of studies have begun to report long-term negative effects resulting from the traditional practice of using a single cut-off date for kindergarten admission and organizing children in one-year age groupings for instruction.

In British Columbia, children may enter kindergarten in September if their fifth birthday occurs by December 31 of that calendar year. The oldest child in the kindergarten class was born on January 31st and the youngest December 31st. This means that kindergarten students are assembled in a class where the oldest child is twelve months older than the youngest, a 20% age difference at this level.

The purpose of this investigation was to examine the effects of these school admission and grouping practices on student learning in British Columbia schools.

The study focuses on all children born in 1990 who reached five years of age in calendar year 1995 and who enrolled in British Columbia kindergarten in September of that year. We follow progress of this population of 46,968 students as they progressed in BC schools through 2010, and compare the performance over time of the youngest students in the kindergarten class with that of the oldest students.


Based on the 1995-1996 cohort, December-born children are 12-15% less likely than their January counterparts to attain Grades 4 and 7 reading and numeracy standards on time, and they are 12% less likely to graduate on time. These "birthdate effects" are evident across the four sub-populations studied: male and females, and Aboriginal and non-Aboriginal students.

Entered Date: 
28 Jun 2011
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