There have been significant advance in educational technology but they have not always brought about measurable shifts in user behavior. This study examined the relationship between teachers' knowledge about a tool and their use of that tool. In many secondary schools use of a Learning Platforms (LPs) is no longer optional although the degree of engagement with the technology remains a matter of choice. However, individual decisions to use selected functionalities of these systems are not well captured in current models of technology acceptance. In a best-case scenario, self-reported possible and actual use of LPs was acquired for 50 teachers from eight technology-rich schools. Three key barriers to use were identified: the functionality of the software, workloads and personal interest. Based on teachers' knowledge of LP functionality and perceived barriers to use, four distinct groups of teachers emerged. A low-user group identified all three barriers, showed little enthusiasm for use of this technology and had a markedly impoverished perception of the LP. There were three distinct higher use groups based on perceived barriers. While the functions used by these three groups showed less variation, with innovative functions such Blogs and Wikis remaining aspirational, there were differences in how such limitations were viewed. Whether the response was one of complacency and frustration has implications for professional development programmes.