Mirrors are sheets of aluminum or silver that are coated in glass. Mirrors work using reflection. Reflection is a property of light. This is when light bounces off a surface. Did you know that every time you see something, light is reflecting off the thing you are looking at! Light can bounce off smooth surfaces in a much orderly way and you can see your reflection on the surface, like a mirror! Mirrors in telescopes or lasers have no glass on top of them, but the mirrors in your house have glass on top. That is to protect the fragile metals underneath the glass. That is how mirrors work!