Question

Because the main goal of high-stakes testing is to upgrade the performance of poorly achieving students, low-income and ethnic minority children are

Answer 1

Because the main goal of high-stakes testing is to upgrade the performance of poorly achieving students, low-income and ethnic minority children are especially likely to be exposed to narrowly focused, regimented teaching.
They do this to them because Children from low-income family tend to not have an additional guideline from their parents because they tend to take two or more job.