The value of checking your work

[mathwonk]

you are quite right to take all the time available. i encourage my students to do this, and am disappointed when they leave early. but in this case i refer to people who did not do well even though they took more than the full amount of time.

 

[mathwonk]

i.e. i do not judge them negatively for taking a lot of time, only for taking a lkot of time and still getting a D or F ("scratching their heads").