This article is about an investigation of six middle school science teachers' beliefs and instructional practice about the coherence of the science they teach as articulated by National Science Education Standards (NRC, 1996). Many well intentioned reform efforts focus on improving content knowledge of teachers, but many classroom teachers regularly miss opportunities to provide conceptual connections within the science ideas building the sense of coherence in science. This investigation involved a quasi experimental study to examine the efficacy of a method for collecting data about middle school science teachers' thinking about science and to determine if they teach science coherently. The teachers were surveyed, interviewed, provided concept maps about their thinking of the science they taught, and observed to investigate whether their practice reflects their beliefs. An examination of the teachers' beliefs, stated and unstated curriculum, the connections among topics and the nature of science revealed that one, the observation tool may have merit for identifying the content and connections among science topics, and two, that teachers' stated beliefs consistent with the National Science Education Standards' vision for coherent science, did not match their demonstrated practice. The content taught could be characterized in three ways; coherent content and few connections, coherent content and connections, and not coherent content. This indicates for this group of middle school science teachers that knowing how they think about science and how those beliefs are reflected in their teaching is complex. This study can inform teacher education and professional development efforts about the need to move beyond just content enhancement to examine prior beliefs about the connections of concepts within science.