My son who is three and a half is all about writing now.  He is constantly writing but reverses letters and numbers.  I know it is developmental but my question is do I correct him and if so how often?

 I think it’s wonderful that he is at this experimental stage as an emerging writer.  Of course you want to encourage him and catch any bad habits before they start, but because of his age you need to go slowly so that he doesn’t get frustrated.   Correct him occasionally but never when he’s tired. There are lots of tools and methods to help him correct his reversals.  The most obvious is to catch him in the act and gently and positively point out the “better” way to form letters.  Or for example, occasionally you could tell him that his “story” is so good you want to make it perfect and have him draw a picture to go along with it so you can give it as a gift to Grandma, hang it on the fridge, or give it to Dad to hang in his office.   

 There are lots of other ways and methods which you can experiment with and change so that the correction process doesn’t become boring or tedious.  Try using a white board and dry erase markers to show him how to form the letters correctly.  Have models of letters around.  Use magnetic letters (see my prior post on magnetic letters).  Playdough is a great medium to let him practice shaping letters correctly.  Tracing and rubbing sand made letters and numbers (white glue & sand to form each letter) works really well at his age.  Basically, the more he sees and writes the letters correctly, his slip ups will lessen in number and eventually disappear.   However, remember that the most important thing in teaching anything to a young child is to do nothing that discourages him.  Even if you do nothing at all to correct him, in time, in all likelihood he will work these errors out with no intervention.