Is it really true that your first hunch is your best hunch.
According to a study by Stoffer, Davis, and Brown (1977) this may
not be the case. 
By examining the students answer sheets for evidence of changes
such as erasures or crossing out the initial answers here is what
they have discovered,
From wrong answer to wrong answer 
15%
From right answer to wrong answer
22%
From wrong answer to right answer
63%
Amazing! So when your teacher asks you to go through your answers
again if you have the time, she knows what she is talking about.
Stoffer, G.R., Davis, K.E., & Brown, J. B., Jr (1977).
The consequences of changing initial answers on objective tests: A
stable effect and a stable misconception. Journal of Educational
Research, 70, 272-277
