Chart explaining the Nuremberg Laws, 
This chart was made when the Nuremberg Laws were introduced. It defined the criteria by which legally made someone a Jew, a person of mixed race, or an Aryan. It was based on the grandparent's heritage, and circles showed whether or not there was any Jewish heritage. Blank circles represented no Jewish blood, Half circles represented half-Jewish blood, and full circles represented full Jewish blood.
For more information on the Nuremberg Laws, click here.