Clarification on Time Usage

I have been using Khan for my son's homeschooling math. He uses it every weekday for 50 minutes, however, the time on his progress report has 2 minutes, 14 minutes, 5 minutes, etc. I know that he is doing the 50 minutes because we set a timer, and he does it in the same room. Are these total minutes or active minutes?

Due to his needs, it's plausible that he is spacing out and therefore inactive, but I don't even know if that's how the computer generates the usage time. I cannot always oversee him and so I often rely on the time report to determine if he has completed his work. I send him back to complete more minutes based on what the report says. This week, however, I know for sure he has completed around 100 minutes, but his report is nowhere near that. 

Help, Please! :)