Usage: The flash cards a are a great medium to teach the basic shapes to baby. Once they learn to make the association between circle and the flash card diagram, try and help them broaden their understanding of the sign by finding circles in your environment. For example they may see circles on the wheels of a car. Or they may see circles in their pancakes at breakfast.
To learn how and when to teach the sign, take a look at the circle page for a video, diagram, and tutorial.