我不知道第一位答主的主张是可以还是不可以，CIC 网站上写了满足最下面三项的其中一种情况，可以在境内申请。

参见 http://www.cic.gc.ca/english/study/study-changes.asp

If you are in Canada as a visitor and wish to apply for a study permit to attend a designated learning institution, you may be able to do so from within Canada. As of June 1, 2014, certain foreign nationals may apply for and receive a study permit from within Canada. These include:

1. minor children studying at the primary or secondary level;
2. exchange or visiting students; and
3. students who have completed a short-term course or program of study that is a condition for acceptance at a designated institution.

CIC官方答案在此。
http://www.cic.gc.ca/english/helpcentre/answer.asp?q=483&t=15
说一下，整个国内加拿大中介圈都在说一个“旅游签转学签”的故事，如果仔细看了这个条文，你就会发现，其实完全是误导。