types of causal relations. In particular, we studied the performance of 101 pre-service elementary teachers who were participating in a class on Science Teaching Methods. We administered a test of causal thinking that involved an extended task from the Test Of Cognitive Development (Demetriou 2001) and two new variations of that task. The first task related to the ingredients of a cake. The second task referred to a strange plant from a planet in another solar system and the different factors that influence its development. The third task concerned the factors that affect the time taken by an ice cream to melt. The students were given information on a series of professed experimental trials in each task and were required to respond to a set of multiple choice questions for each task, each time identifying the type of causal relation connecting the two variables. Additionally, the students were required to explain their reasoning in each case. The data were analyzed qualitatively. The results provide useful information on the performance of these students with causal reasoning tasks as well as on their ability to elaborate on the reasoning they follow to arrive at specific conclusions. We will discuss the implications of these results for teacher preparation programs that aim to promote the development of scientific thinking in a wider educational context.