A field trip is a school outing, one which usually has some educational purpose. Many field trips are taken to museums.
While you may go on a field trip with your dance class, camp, or other group, they're most often taken as school groups. An entire first-grade class, for example, might take a field trip to the zoo, while graduating high school seniors might go on a field trip to an amusement park. Outside of the US, a field trip is typically called a "school trip."