Québec reopened schools outside Montréal in May. Weekly case counts:

25 mai : 19 cas d’élèves
31 mai : 44 cas d’élèves
5 juin : 34 cas d’élèves
12 juin : 10 cas d’élèves
19 juin : 6 cas d’élèves
 
Source: Ministry of Education. https://twitter.com/cbcnews/status/1296884896812666881

According to public health, most of the cases were one-offs who walked in with it. There was one outbreak affecting an entire class of a dozen or so.

Public health, the Québec government and the unions considered this return a success.

From these results you can be fairly sure there will be dozens of cases among Canadian students in early September and that most of them will have caught it outside school.

May you be blessed with health authorities and news outlets able to calmly tell you the difference.