[Source: Science Daily]

Researchers found that 4-year-olds in Head Start classrooms that included higher concentrations of 3-year-olds were up to five months behind in academic development compared with their peers in classrooms with fewer younger children.
That’s a problem because, as of 2009, about 75 percent of all Head Start classrooms were mixed-age. Head Start is a federal preschool program that promotes the school readiness of children in low-income families from age 3 to age 5.
“While there has been some enthusiasm for mixed-age classrooms, our results suggest there may be a significant downside for older children,” said Kelly Purtell, co-author of the study and assistant professor of human sciences at The Ohio State University.
“Four-year-olds are often enrolled in classrooms that are less supportive of their academic learning.”
The results may also help explain why a 2010 national evaluation of the Head Start program found that it was only modestly effective in helping the academic achievement of 4-year-olds.
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