Then pour a different “A” cup into the purple AB blood type.ĩ. Since the color changed to purple, Type A blood and Type B blood are not compatible. Next, pour another red “A” into a blue type “B” cup. Once you’ve recorded that data, discard the cup.ħ. Since the color did not change, blood Type A is compatible with blood transfusions with blood Type A. Pour one of the red “A” blood type cups into another one of the “A” blood type cups. Leave only water in the last four cups this will represent blood Type O.Ħ. Put blue and red food coloring in four more cups to make a purplish color this will represent Type AB blood.ĥ.