Studies of tracking show that children placed in nonacademic tracks tend to come from

Studies of tracking show that children place in nonacademic tracks tend to come from low-income households, one parent families, and minority groups in which tracking is the preparation of placing students in precise curriculum groups on the basis of test scores and other criteria. In addition to sociology, the correspondence principle denotes to the predisposition of schools to endorse the values likely of individuals in each social class and to continue social class separations from one generation to the next.

What was the length to begin with?