Oh, you already knew that? Well, just in case no one believes you, it has been verified by the National Research Council. Here's a bit of a soundbite to give your relatives (emphasis mine):
"Learning is broader than schooling, and informal science environments and experiences play a crucial role," said Philip Bell, co-chair of the committee that wrote the report, and associate professor of learning sciences at the University of Washington, Seattle. "These experiences can kick-start and sustain long-term interests that involve sophisticated learning. Think of the child who sees dinosaur skeletons for the first time on a family trip to a natural history museum, and then goes on to buy dinosaur models and books, do Web searches about dinosaurs, write school reports on the subject, and on and on." and "...even everyday experiences such as a walk in the park, contribute to people's knowledge and interest in science..."
Read the press release here.
It's a good thing we have organizations that will study such things. Otherwise, how would we ever know that learning can take place in museums or on a nature walk? And while this study specifically examined science education, do you suppose that students might learn about other subjects outside the traditional classroom?