<p>I tend to be obsessive compulsive about ensuring that the bubbles on the scantron are filled in completely and darkly, and I'm afraid that this could be wasting a lot of time. How sensitive are the machines that read the scantrons?</p>
<p>i do this a lot too... anyone?</p>
<p>good question. I occasionally have the same issue.</p>
<p>i am a student aide for a teacher at my school</p>
<p>i get scantron duties all the time and the machine that we have is fairly new. often times the teacher gives me an answer key to the test and the bubbles are just crossed off with one swipe of a # 2 pencil. so basically u see a semi thick strip of graphite in the middle of the bubble. the machine always reads it correctly.</p>
<p>so dont spend too much time darkening in those bubbles. even a thin layer of graphite is enough to block light and that is what scantrons read..the light permeations.</p>