"You have two hours to complete the assignment. If you finish early, work on your presentation for the next class; you may not leave until the end of the period."
I spent two hours last evening in a college classroom, watching as ten students did a writing assignment. To their credit, all of them spent at least some of the time pounding away on the keyboards.
The first to arrive in the class dove into the assignment, asked a couple of pertinent questions, and was also the first to finish. He then used the rest of the time period to do research for the next assignment, even printing out some information he needed for it.
Another student spent a good ten minutes asking other students what he was supposed to do, apparently having decided that I know nothing and am just sitting here to make sure they don't steal the computers. He also then interrupted others by telling them what he was going to write and asking what they thought of it.
One, who appeared to have finished his work early but did not turn it in, then sat at the computer checking his email. He was also chatting with another who had finished and turned in her assignment.
At different times, three of them left the room, ostensibly to use the rest room. I guess they didn't think I could see them pulling out their cell phones as they went out the door.
One of them left and went to a vending machine somewhere. He came back with some chips and a beverage which I hoped did not constitute his dinner. Unfortunately, it probably did.
Two of them, neither of whom appeared to be finished, were high-fiving each other, presumably on their jobs well done.
It occurred to me as the second hour was winding down that the ones who appeared finished but hadn't turned in the work were stalling in case I was going to point out that they could be working on another assignment.
And when the two hours were up, four of them were still not finished, though three of them wrapped up in a minute or two. The last one asked for five more minutes; he actually needed seven. And then he had to reprint his assignment because he realized he left something out.