The study will also help to determine whether changing treatment for children and adolescents with ALL with high levels of minimal residual disease may improve cure rates. Measuring minimal disease (MRD) is a laboratory test that finds low levels of leukemia cells that the investigators cannot see under the microscope. In the past, it has been shown that children and adolescents with ALL with high levels of MRD after one month of treatment are less likely to be cured than those with low levels of MRD. Therefore, on the study, the bone marrow and blood at the end of the first month of treatment will be measured in participants with leukemia, and changes in therapy will be implemented based on this measurement. It is not known for sure that changing treatment will improve cure rates. MRD levels can only be measured if the marrow is filled with cancer cells at the time of diagnosis. Therefore, MRD studies will only be done in children and adolescents with ALL and not in those with lymphoblastic lymphoma.