Yes, it is possible.
Quote: "If you are changing schools and/or your program of study but remain at the same level (e.g., secondary level), you do not need to modify your study permit.
However, if for example you are a student at the primary school level and you are moving on to secondary school, or if you are a secondary school student and you are moving on to post-secondary studies, or if you are moving from post-secondary studies to secondary studies, you need to submit an application to modify your study permit at the Citizenship and Immigration Canada Case Processing Centre in Vegreville, Alberta."