Choose a time of day when the light is dim or darken the room by pulling shades or curtains.
Hold an egg to be candled by the ends. Position the egg so that the center of the egg will have an unobstructed view.
Turn on a flashlight. Adjust the beam, if necessary, so that it is tightly focused. Choose a flashlight that is bright and easy to hold to candle eggs.
Hold the egg up to a comfortable viewing position in front of you. Position the flashlight behind the egg so the beam shines directly into the egg.
Look at the contents of the egg to determine if only the yolk is present or if an embryo is beginning to develop. Also look for small rings or a dimpled pattern as a sign of bacteria presence.