Who is that person in the mirror? It seems to be another you, doing exactly what you are doing.  How can a mirror copy you?  A mirror is very smooth.  The front of a mirror is flat, polished glass.  Behind the glass is a thin layer of shiny metal.  As you stand in front of a mirror, light bounces off you an passes through the glass.  When the light hits the shiny layer behind the glass it bounces straight back.  This is why you can see yourself. Your reflection is a good copy of you.  But have you ever tried to shake hands with it?  You can't.  When you holds out your right hand, your reflection holds out its left hand.  Why does your reflection do just the opposite of what you do? Pretend for a moment that the mirror is something you could fall into-like a soft layer of fresh snow.  If you fall into the snow face down you leave a perfect print of yourself.  Your snow print is like your reflection in the mirror.  Your right hand makes the left hand of tour snow print, and your left hand makes the print's right hand.  A mirror works in the same way.  The light bounces straight off each part of you and into the mirror.  The shiny surface behind the glass bounces the light straight back.  So the reflection you see is a   light print.  Each part of you makes the opposite part of your reflection in the mirror.  What do you think will happen if you print your name and hold it up to a mirror? Try it and see.