This study describes the planning activities of 12 in-service elementary school teachers in Quebec. Theureau's (2006) course-of-action theory was used to document the teachers' life course relating to their planning activities over an entire school year. Semi-directed interviews were conducted using authentic planning materials (agendas, workbooks, schedules, etc.) used by teachers in order to describe their activity as it unfolds over time. The results show that teachers for all school subjects concurrently, mainly differ according to the timeframe involved (short, medium, long-term). Their concerns remain largely unchanged over the three timeframes, except that they are fleshed out in more detail for the short term, particularly with regard to the complexity of taking into account the pupils' characteristics, the teachers' situation and the collaborative nature of these activities. Results also describe how their planning activities are supported by multiple actions and communications over an entire school year.