The objective of this study is to estimate the feasibility and acceptability of cognitive training in the virtual reality setting with children undergoing radiotherapy for brain tumors. To achieve this goal, the investigators plan to study children undergoing radiotherapy for brain tumors randomly assigned to cognitive training administered via an iPad or virtual reality. Both groups will also participate in cognitive testing and exams using functional near infrared spectroscopy (fNIRS) pre- and post-intervention. The questions to be investigated are: 1. Will cognitive training via virtual reality be feasible and acceptable for children undergoing radiotherapy for brain tumors as indicated by participation rates, adherence and frequency of side effects? 2. Will cognitive training via virtual reality provide neurocognitive benefits? 3. Will there be predictable changes in brain activity as measured by neuroimaging? Findings from this study will be used to develop a larger, definitive trial with direct potential to improve cognitive outcomes for children treated for cancer using a safe and effective alternative to desktop- or laptop-based computerized cognitive interventions with great promise for improving quality of life.