STAFF PHOTO BEN GOFF Brothers Austin Brandenburg, 13, front, and Andrew Brandenburg, 11, from Bentonville, help Wednesday set off a choreographed show of Mentos and diet soda reactions at the groundbreaking for the Amazeum museum in Bentonville. The event was held at the adjacent First Presbyterian Church. The Amazeum will be near the entrance to Crystal Bridges Museum of American Art and is scheduled to open in the second half of 2015.