The difference between being sick and feeling exhausted is that when you're sick, there's a virus involved which causes a disease and makes you ill.
Feeling exhausted on the other hand is slightly different. You feel physically or mentally drained due to overworking, stress and exercising.
Cell phones in the classroom cause too many distractions.
A good plot imposes an artificial order on events because the events must move to an end logically and naturally. I mean, they should do so, because if it is an illogical order, not many people are going to understand what's going on. So a good plot and some kind of an order may help with this/
It's excavate. The meaning straight from the dictionary is "remove earth carefully and systematically from (an area) in order to find buried remains." which is my proof for it. Have a good day!