Situational interest is short-term interest that is linked to environmental factors in a particular situation. Previous studies have found that some science teaching techniques can be very effective in generating situational interest among students, but the reasons why these are effective remain unclear: Hands-on activities, for example, are known to generate situational interest, but there is little consensus about the underlying reasons why. The purpose of this study was to investigate the underlying causes of situational interest in a range of science teaching techniques. The participants were 229 Australian preservice elementary teachers in a one-semester science course. An open-ended survey was administered on three occasions during the course, and individual interviews with a subset of 25 students were held at the end of the semester. The teaching techniques that generated situational interest included hands-on activities, personal anecdotes, fun facts, demonstrations of science toys, science magic, clear explanations, and the use of models and artifacts. For each technique, situational interest was due to a combination of three underlying causes: success, relevance, and novelty. It was concluded that substantial situational interest occurred when these students successfully learnt something that had novelty and personal relevance. It was concluded that this triadic combination represented the underlying causes of situational interest in the course.