Hi @guo848,
The "Total Activity" column of the "People" area of a Canvas course can be a bit of a mystery.
What I can say is that the How do I use the People page in a course as an ins... - Instructure Community - 667 support article does have an official definition/answer.
Total Activity — allows you to see how long users interact within a course and counts page navigation only. Total activity time is displayed in hours:minutes:seconds. If a user has not yet reached an hour of activity, total activity time is displayed as minutes:seconds. Total Activity records any time spent viewing course content that exceeds two minutes. If the time between a new activity and the last completed activity is under ten minutes, all time between these two events will also be included. Total Activity does not include group activity or page views for videos that do not include intermediate page requests, such as a half-hour recorded lecture. To view specific page views for a student, view the student's course access report.
Depending on the design of the course, the type of content, and an instructor's expectations, I do not find it to be reliable and the same could be said about almost any other website on the Internet.
-Doug
