Edmonton parents of would-be kindergartners are about to make a major decision — whether to register their children for school or hold them back for an additional year.

For some families, the idea of delaying enrolment would be unthinkable. But the practice of 'redshirting' - named for the jerseys worn by college athletes kept out of competition for a year- is becoming increasingly commonplace.

When the cut-off date for kindergarten registration in Alberta came and went on Monday, hundreds of families decided to wait rather than rush to the registration office.

Proponents of redshirting believe the oldest, most physically and mentally mature students in the classroom are the most likely to succeed.

"There's a significant cognitive gain to be oldest kid in the class," said Justin Smith, an associate professor at Wilfred Laurier University, who believes redshirting will give students an edge.

"Beyond test scores, these kids are more likely to be school leaders, taking part in clubs and things like that as they get older."

In his research, Smith compared B.C.'s oldest students (those born in January) to its youngest (those born in December) and found the January kids outperformed the younger students by seven percentage points in math and reading tests.  But by Grade 10, the January birthdays outperformed the December kids by just two percentage points.

The academic community remains divided over the benefits of redshirting.

"Kids that are redshirted do not really, in the long term, benefit," said Linda Cameron, a  professor with the University of Toronto's department of curriculum, teaching, and learning. "There may be short-term benefits, but it diminishes over time."

Cameron said redshirting creates an uneven academic playing field. Older children may actually feel out of place, even bored,  in a classroom of younger peers. Furthermore, she said redshirting could ultimately become a self-defeating trend as more and more parents delay enrolment.

"If you consider real education — socially, emotionally and intellectually — test scores don't really adequately measure those things, especially when you talk about really young kids," said Cameron, a mother of three and a grandmother to four.