Participants will be given several different chemotherapy drugs during many periods of treatment (called "phases"). These drugs are known to kill lymphoblastic cancer cells. Some of the drugs are given by mouth, some into the veins (intravenously), and others as an injection (a shot) into the muscle. Some chemotherapy drugs will be given directly into your spinal fluid (called intrathecal chemotherapy) during a lumbar puncture (spinal tap). This treatment helps prevent the cancer cells from coming back in the spinal fluid and brain.