Washington Redskins general manager Bruce Allen says the team is inviting 500 area high school football coaches to a concussion forum during a minicamp next month. Speaking Wednesday at a panel discussion as part of Brain Injury Awareness Day on Capitol Hill, Allen said the Redskins have sent a letter to coaches in Washington, Maryland and Virginia, asking them to attend practice at new coach Mike Shanahan's first minicamp and participate in an information session about concussions.