Although teachers in principle are prepared to make use of science centers, such excursions often fail to facilitate learning processes. Therefore, it is necessary to improve the link between science centers and schools. The design and evaluation of valuable outreach projects may enhance students' out-of-school science learning. In our study, we developed a curriculum-based lesson for fifth graders as part of the educational program of a salt mine as out-of-school learning site. The complete program comprises a guided tour along the visitors' gallery and simple experiments about important physical and chemical properties of salt (NaCl). We evaluated the impact of students' previous knowledge and experiences and of the surroundings at the learning setting itself, considering students' cognitive and affective outcomes. The results revealed the appropriateness of the lesson for fifth graders with regard to its difficulty and design: The learning setting provided premises for substantial learning processes and positive feedback. Yet, students' outcomes were independent of the setting: students did not benefit from the subject-related surroundings at the salt mine themselves. These results encourage the careful development and usage of learning settings that foster out-of-school science education. (Contains 4 tables and 2 figures.)