The 21st century is about 31/2 feet tall, weighs about 40 pounds and is toddling into kindergarten this autumn.

When this year's kindergartners don cap and gown and march up to receive their high school diplomas, it will be the spring of 2001.These children will be filling the work force early in the next century when international competition will be more intense than it is today. And they'll be supporting the huge baby boom generation in its sunset years.

Yet these youngsters are going into a school system that has been criticized for being worse than the one that educated their parents. It produces students who can't read, write or calculate, who can't locate the United States on a map of the world and who don't know when Columbus discovered America.

And these kindergartners have been raised differently than thier predecessors. For the first time, more than half of all mothers are back to work before their children are a year old. A large number have been raised by a helter-skelter system of day-care centers, housekeepers and relatives.

A larger percentage of these children will be lower-income Hispanics and blacks because whites - especially urban professionals - have such a low birthrate. More will come from families in which Spanish is the dominant language because immigration from Hispanic countries has reached record numbers in recent years.

Add to that the large number of children raised by single parents - usually mothers - who generally have lower incomes, and the poverty rate for today's kindergartners has reached higher than 24 percent.

Because a large number of children now are born to poor, young mothers who have not had proper prenatal care, as many as 250,000 of this year's kindergarten class were born with low birth weights, making them more likely than others to be educationally impaired.

"While there will be more kindergartners than last year, most of the growth will be minority youngsters," said Sam Sava, director of the National Association of Elementary School Principals. "Most of the growth will be youngsters from an economically deprived environment. And most of the growth is in states that have the highest dropout rates."

The academic gap between pupils also will be larger, he said. Many youngsters come from families that have helped them with pre-school and home learning and are ready to read. Many others, who come from families that provided no help, still need to learn their colors.

They're going into classes that have 25 to 30 pupils per teacher, he said, even though most studies show that if kindergartners are to receive the type of early help they need, class size should not be larger than 15.

Yet too much is at stake for these kindergartners to be treated like so many of their predecessors. Labor, especially highly skilled workers, is expected to be in short supply early in the next century. Poor black and Hispanic students, who in the past have sat on the low side of test scores and the high side of dropout rates, will be the key to American competition with Western European and Asian countries.

In the past, workers have been able to get by reading on a fourth-grade level. But by the time today's kindergarten class reaches the work force, most of the better paying blue-collar jobs will require reading on at least a 12th-grade level.