Actually, two lessons. 

The first lesson:  The computer can't shut down while a print is running. So, if the settings on the computer go to sleep after, say, 1 hour, and the print runs for 2 hours, you'll end up with half a print. 

Lesson two: In a middle school classroom, the computer setting are not the only thing that shuts down the computer. Actually, there are 25 things. 24 of which are students. Someone shut the lid on the computer running our printer, so we ended up with half of a (very lengthy) print. The low-tech solution in the picture above works pretty well so far. 

By Jane (7th grade)