One of my students this semester, Bill Ward, sent me this interesting brain-teaser.
FINISHED FILES ARE THE RESULT OF YEARS
OF SCIENTIFIC STUDY COMBINED WITH THE
EXPERIENCE OF YEARS.
Count the Fs in that sentence ONCE and ONLY ONCE. How many Fs does the sentence contain?
The answer can be found here
This little quiz is a reminder of how difficult proofreading can be. When we are tired or lack focus, our brains don't always proofread accurately. "Is" looks like "in" and "it," and "on" looks like "of" and "or."
I am a fan of proofspeaking. As silly as its sounds, one of the best ways I have found to catch typos and odd-sounding sentences is to read your document out loud, slowly, sounding out every word. Try it sometime and see if your errors don't jump off the page.