Science education researchers agree about the importance of evidence in science practices such as argumentation. Yet, disagreements and ambiguities about what counts as "evidence" in science classrooms pervade the literature. We argue that these ambiguities and disagreements can be viewed as falling along three fault lines: (i) the…

Through analysis of a classroom lesson led by a decorated teacher, we illustrate how instructional practices favor students seeking empirical patterns at the expense of using mechanistic reasoning. In the lesson, when students spontaneously come up with hypothetical mechanisms to explain why a light bulb in an electric circuit does or does not…