DALLAS (AP).- Former President George W. Bush said Monday that his presidential center will be a venue for learning and action, and that it already exceeds his expectations. The George W. Bush Presidential Center will feature a presidential library and policy institute when it opens in spring 2013. Bush said the institute, which will focus on education reform, global health, human freedom and economic growth, will help him to stay involved in the areas that interest him. “The challenge is after you are president to make sure you are still constructive, that you add something to society,” Bush told some 600 people gathered at a ceremony to mark the placement of center’s last construction beam. “I thought long and hard about how I wanted to do that.” He described the center as “an exciting place. A place of learning, a place of scholarship, but most importantly, a place of action.” The nearly 225,000-sq.-foot center is located on