This paper investigates whether and how primary school students improve their epistemic understanding about a particular aspect of the nature of inquiry (NOSI), namely, the 'non-linear nature of inquiry' through an explicit-reflective or implicit instruction. The sample consisted of 30 5th grade students, who were randomly divided into two groups: the implicit -- T1 (N = 14) and the explicit -- T2 (N = 16). Instruction followed an inquiry model, lasting fourteen (14) hours for each group. T2 was taught the non-linear nature of inquiry explicitly, in contrast to T1, which was expected to acquire such understanding without direct instruction regarding NOSI. A written questionnaire in conjunction with individual semi-structured interviews was used to assess students' views before and after instruction. Content analysis was conducted with the data from the written questionnaire and the interview transcripts. The pre-test showed that students seem to argue over the alternative view on the linear nature of the inquiry procedure. The post-test results support that epistemic understanding of the explicit group were significantly improved towards more informed levels in contrast to the implicit group, whose epistemic understandings appeared not to change or in some cases fell to a lower level.