Although implicit approaches for teaching NOS are the dominant model for research apprenticeships, at least as reported across the literature (Sadler et al., 2010), some apprenticeship programs have adopted more explicit approaches. For example, Charney and colleagues (2007) studied a four-week apprenticeship program for high school students. The mentor scientists involved in this work modeled their own reasoning practices and consistently posed questions that demanded critical reflection on NOS constructs through a series of seminars. Students kept journals in which they responded to reflective prompts on a near daily basis. Students completed an open-ended NOS questionnaire before and after the experience as a means of assessing potential NOS gains. Results indicated that most students’ conceptions of NOS shifted towards more sophisticated understandings of the tentative nature of scientific knowledge. The authors attribute this shift to the to the explicit/reflective nature of the program itself.