High school students are not the only ones missing school. Chronic absenteeism in the elementary grades is a major problem, too, especially in districts with a high concentration of poor and immigrant students (see chart), according to a report released this morning by the Center for New York City Affairs at the New School.

Twenty percent of kids in the city’s elementary schools missed more than a month of school during the 2007-2008 school year, researchers found while investigating whether attendance systems put into place after the death of Nixzmary Brown are catching child abuse before it becomes deadly. In some schools, more than 40 percent of students missed that much school, making them “chronically absent.” The numbers vary widely across the city, as the but also within individual zip codes, the report points out.

Why does absenteeism matter? New research shows that kindergarten — which is not mandatory in New York State — is essential to academic success. “Among poor children, chronic absence in kindergarten predicts the lowest levels of educational achievement at the end of fifth grade,” concluded a recent report out of Columbia University’s National Center for Children in Poverty.

The Center for New York City Affairs report indicates that patterns of school non-attendance begin early in a child’s school career, said Clara Hemphill, the education reporter who was senior editor for the report (and who was also my boss for a time at Insideschools.org, the Web site she founded).

“The DOE has poured millions of dollars into reforming high schools, but this report shows that by high school much of the damage is already done,” she said.