Join Minerva when the intelligent and mobile robot guides tours of the "Material World" exhibition, Monday through Sept. 5 at the National Museum of American History, 14th Street and Constitution Avenue NW (Metros Smithsonian, Federal Triangle). The robot-led tours are offered from 10 to 3 (start times vary). The "Material World" exhibition features more than 400 artifacts that illustrate how much materials such as wood, metals and synthetics influenced how we live. On Thursday at 10:30, Minerva's 10 inventors will describe their work in the museum's Information Age Theater. The museum is open from 10 to 5:30 daily; admission is free. Call 202/357-2700 (TDD: 202/357-1729).