and Brewer, 1992) argue that learners build coherent theories, much like scientists, by integrating their experiences, and others (e.g., diSessa, 1988) argue that scientific knowledge is often constructed of many small fragments that are brought to mind in relevant situations. Either way, small pieces of insight, inferences, or understanding are accepted as vital components of scientific knowledge-building.
Most traditionally valued aspects of science learning fall into this strand: models, fact, factual recall, and application of memorized principles. These aspects of science learning can be abstract and highly curriculum-driven; they are often not the primary focus of informal environments. Assessments that focus on Strand 2 frequently show little or no positive change of Strand 2 outcomes for learners. However, there are several studies that have shown positive learning outcomes, suggesting that even a single visit to an informal learning setting (e.g., an exhibition) may support development or revision of knowledge (Borun, Massey, and Lutter, 1993; Fender and Crowley, 2007; Guichard, 1995; Korn, 2003; McNamara, 2005).
At the same time, studies of informal environments for science learning have explored cognitive outcomes that are more compatible with experiential and social activities: perceiving, noticing, and articulating new aspects of the natural world, understanding concepts embedded in interactive experiences, making connections between scientific ideas or experiences and everyday life, reinforcing prior knowledge, making inferences, and building an experiential basis for future abstractions to refer to. Informal experiences have also been shown to be quite memorable over time (see, e.g., Anderson and Piscitelli, 2002; Anderson and Shimizu, 2007).
While the knowledge of most learners is often focused on topics of personal interest, it is important to note that most people do not learn a great deal of science in the context of a single, brief “treatment.” However, this ought not to be considered an entirely negative finding. Consider that learning in school is rarely assessed on the basis of a one- or two-hour class, yet science learning in informal environments is often assessed after exposures that do not exceed one to two hours. Falk and Storksdieck (2005) found that a single visit to an exhibition did increase the scientific content knowledge of at least one-third of the adult visitors, particularly those with low prior knowledge. However, even participants whose learning is not evident in a pre-post design may take away something important: The potential to learn later—what How People Learn refers to as preparation for future learning (National Research Council, 2000). For example, visitors whose interest is sparked (Strand 1) presumably are disposed to build on this experience in the months that follow a science center visit by engaging in other informal learning experiences.