We focus on the means to support the use of ICT by math teachers. Despite the availability and accessibility of ICT tools and the recommendations in the curricula in many countries to use it, teachers are reluctant to use technologies. In the case of dynamic geometry systems (DGS), several reasons explain this resistance. The multiplicity of DGS and resources makes it difficult to identify relevant and quality resources. Moreover, the availability of resources does not solve the problem of their appropriation by teachers, which requires an evolution of teachers' competencies and their conceptions about the role of technology in teaching and learning of mathematics. These considerations have led to one of the goals of I2Geo project, which is at the core of this contribution: a quality assessment process for dynamic geometry resources based on an evaluation of resources by users. In order to frame the resource evaluation, we have designed a questionnaire addressing aspects that contribute to the mathematical, instrumental, didactical, pedagogical and ergonomic quality of a resource. The aim is to collect users' opinions reflecting the use of resources in a classroom and thus stimulate their reuse by others and their improvement. Several experiments that have been carried out with groups of teachers allowed analysing strengths and limitations of resource quality assessment. It turns out that the questionnaire is a helpful tool for the appropriation of resources since it prompts teachers to analyse in detail main aspects of a resource that each criterion of the questionnaire addresses.