This paper shares presents some theoretical issues concerning teachers' professionnal genesis with spreadsheets by bringing closer the results abtained in different research. It aims at gaining insight into the teachers practices with technology and how these practices evolve in time. Comparing the evolution of an ordinary teacher integrating spreadsheet in her practices with the practices of teachers expert with spreadsheet, we find some similarities in the way of using this tool, and make some hypotheses on the importance of these common elements as key issues in ICT integration.