Since the mid-1990's, when zero tolerance took root, the expulsion rate has soared as much as 800 percent in some cities.

They are plenty old enough to be expelled, the first national study of expulsion rates in prekindergarten programs has found.

Because the study is the first of its kind, it is impossible to say whether expulsion rates are increasing.

But these programs, the Yale study found, had lower expulsion rates than faith-affiliated and other private preschools, which tend to stress academics.

High expulsion rates also often flag a preschool's failure to provide support for its teachers.

The addition of this central disc lowered the IUD's expulsion rate.

As "managed moved" pupils do not count in official exclusion data, the national expulsion rate, published later this month, is artificially low.

Not all Connecticut school officials believe that the state's suspension or expulsion rate is terrible news.

"Our expulsion rate is probably up there," he said.

In Chicago, the expulsion rate has jumped nearly tenfold in the last three years.