The purpose of this study is to find out if strict rest for 5 days helps children get better after concussion. This research is being done because, currently, there is no effective treatment for concussion. Physical activity (for example; running, playing sports) and brain activity (for example; homework and tests) may make concussion symptoms worse. We are studying whether strict rest after concussion may help improve symptoms. About 110 children, ages 11-22 years old will take part in this study at the Children's Hospital of Wisconsin. This study is being funded by the Injury Research Center. The research grant pays for study procedures, follow-up testing, and patient reimbursement. Research staff is not being provided incentives to enroll subjects.