It would be highly desirable to confirm these assertions using the well-respected large-scale science assessments such as NAEP, PISA, and TIMSS. And while those assessments sometimes show strong positive correlations between informal learning experiences out of school and scale scores on the assessments, they provide only correlation data, and cannot demonstrate causality. Furthermore, the assessments largely restrict themselves to the cognitive realm, to trying to learn what students know and can do in science, but not whether they care about science.
There is an attitude among some scientists and science educators that cognitive accomplishment is the only result which matters. “I don’t care whether students hate science and engineering or not, as long as they learn it. Only the students who go on to careers in STEM need to like it” (private communication to the author). For formal and informal STEM educators to maximize the complementary aspects of their approaches, some resolution of the positive and negative attitudes about free-choice learning needs to be achieved, including performing rigorous longitudinal research on the impacts on individuals from both formal and informal learning. Some of this research is now underway. If a couple of percent of the resources devoted to international, national, state, and local assessments of formal learning were devoted to assessing informal learning, we would have much more evidence about the anticipated value of learning outside the classroom.