Hi Sheere,

I question the "15 second rule" as I'm guessing you read on this page How do I view a quiz log for a student? .  I question it based on your results and even the screenshots on that page.  They show the Stopped viewing alert within the same second of viewing.  

My personal take on any logs is that they only tell a part of a story and there probably are things that could interfere with them being accurate.  Canvas can really only log what is going on inside of the browser window it's running in.  And I have that being able to report that someone left a page is somewhat controlled by the web browser itself.  I also bet that things like Add ins or browser extensions could impact some of the information gathered in these type of logs. 

Just my thoughts above.  Looking at your logs I'm inclined to believe that the student viewed another tab or browser window at the points marked in red, but I would be considering many other things before accusing the student of that.

Rick