Analogies as tools for meaning making have been of interest to scientists, educators and philosophers ever since Aristotle with their use for reasoning being suggested as a key process in human cognition from early childhood to late adulthood. Extensive research in the area of students’ learning has also consistently found that analogies as instructional tools can play a significant role in facilitating students’ attainment of a conceptual understanding in science. Studies in this area, however, have mostly focused on whether and how analogies provided to the students by teachers and/or researchers can be used effectively in instructional settings. Very few studies have been carried out on the self-generation of analogies by students and how these can be used by the latter in order to understand new information and reason in novel situations. This paper reports on a cross age study in which Greek students from five different age groups (primary and secondary education) were asked to make predictions in situations they had not considered before and describe the reasons that led them to these predictions. According to the findings, students made use of analogies rather than scientific thinking in order to reach a conclusion and make a prediction. In many cases, this analogical reasoning was a non-scientific one as it was based on students’ experiential knowledge. This non-scientific reasoning led most of them to make a prediction incompatible with the scientific account but there were also cases in which analogical reasoning was effective in assisting students to understand the novel situations and reach a conclusion/prediction compatible with the scientific account. A cross age comparison of the predictions and the reasons underpinning them showed that students across the five age groups were making the same incorrect predictions as they were reasoning on the same or similar analogies. The discussion of the results point to the need for a better consideration of the analogies students use, and how/why their reasoning on the basis of such analogies could make them misunderstand novel situations.