Why do students reverse letters?

When most people hear the word dyslexia, they think about reversing letters. While many dyslexics DO have letter reversals, so do many young non-dyslexic children. Why is this?

The explanation that has made the most sense to me, and the one I use when explaining to students and parents, is this. I hold up a pencil: "What is this?" "A pencil," the student says. I turn the pencil upside-down. "Now what is it?" "A pencil," he replies. I do this several times, rotating the pencil each time, and always the answer is a pencil. Then I hold a d letter card up: "What is this?" "A d," he says. I rotate the card: "Now what is it?" "A p." What worked for the pencil doesn't for the letter.

Up to now in a child's experience, an object remains the same object any way it is positioned. Letter and number symbols are the first thing a child encounter in which the positioning matters. It's a different object with each different orientation, or perhaps it's no object at all. A pencil can't be "backwards", but a letter or number can. So of course it's confusing, and most young children reverse their letters at some point. I gently correct and teach them how to "make their bed" (a way to hold their fists to make a bed and see the correct orientation of b and d). Generally this goes away with time and familiarity with the language. If it hasn't by second grade, it's time to take a second look.