Many primary school teachers in Australia tend to be reluctant to teach science. partly because they are not confident in science and have limited science background knowledge. However, quite a number of primary school teachers still manage to teach some science. When they plan to teach science, many of them use the term "science activities that work." Such activities seem to be related to science pedagogical content knowledge for some primary teachers. In order to better understand what the term "activities that work" means, twenty teachers from several schools were interviewed and asked what they understood by this expression. Themes that emerged suggest that activities that work are hands on, are interesting and motivating for the children. have a clear outcome or result, are manageable in the classroom. use equipment that is readily available, and are preferably used in a context where science is integrated into themes. Implications for curriculum and for preservice teacher education are considered.