Understanding the science in a "socio-scientific issue" is at the heart of the varied definitions of "scientific literacy". Many consider that understanding evidence is necessary to participate in decision making and to challenge the science that affects people's lives. A model is described that links practical work, argumentation and scientific literacy which is used as the basis of this research. If students are explicitly taught about evidence does this transfer to students asking questions in the context of a local socio-scientific issue? What do they ask questions about? Sixty-five primary teacher training students were given the pre-test, before being taught the "concepts of evidence" and applying them in an open-ended investigation and were tested again 15 weeks later. Data were coded using Toulmin's argument pattern (TAP) and the "concepts of evidence". After the intervention it was found that, in relation to a socio-scientific issue, they raised significantly more questions specifically about the evidence that lead to the scientists' claims although questions explicitly targeting the quality of the data were still rare. This has implications for curricula that aim for scientific literacy. (Contains 5 tables and 2 figures.)