In education, teachers, for whom profession will require an informed-based practice, and administrators, who must account for results in the face of resources reduction, will need research. Frequently overlooked, there is a method which can facilitate this junction: single case design. The procedure consists in the measure of a factor several times on one or a few cases before as well as during a treatment. Visual inspection from the comparison of the measures before and after will say something about the impact of treatment. The article will present the method and an example from education, after which the principal advantages and disadvantages of single case design will be reviewed.