The study stemmed from the fact that teachers have difficulties in designing lessons. The objective of the study was to identify these difficulties and to analyse how to adapt lesson plans in the context of the paradigm shift in the educational system through its focus on competence training. We analysed 40 lesson plans for themes at the subject "Mathematics and Environmental Exploration" for the preparatory class. These lesson plans were developed by third-year university students who were teachers and educators that completed full time courses and distance learning at the specialization "The Pedagogy of the Primary and Preschool Education", during the 2014-2015 academic year. We analysed the titles of the plans, the introductory part of the plans (class, grade level and date, subject, curriculum area, thematic units, the lesson type, the specific competences, the operational objectives, the organization of work, methods and processes of teaching, means of education), and lesson development. We identified the problems that teachers had in designing the lesson and we made some suggestions for solving them.