FREDERICKSBURG, Va. (AP) – Bill Cosby has pledged to give at least $1 million toward a planned National Slavery Museum. “We need history,” the entertainer told an audience Friday night in Fredericksburg, where the museum is planned to open in 2007. “We need proof for our children … to see the strength of their ancestors.” Cosby announced he would donate the proceeds from 10 of his concerts to the U.S. National Slavery Museum effort, between $1 million and $1.5 million, museum officials estimate. The museum also plans spin-off fund-raising activities around each of those concerts and hopes to raise $20 million, according to Ed Wegel, chairman of the museum’s capital campaign committee. Former Gov. L. Douglas Wilder, the nation’s first black elected governor, has estimated the museum project will cost $200 million. Construction on the five-story, 250,000-square-foot building is scheduled to start later this year. Cosby sits on the museum’s board.