Dragons 

This is a cool interactive. You get to mix Dragon Genotypes to get particular Phenotypes. 

Here you see how heterozygous combinations result in the expression of the Dominant Allele as seen in the phenotype. Whereas the recessive allele is only expressed as a phenotype when you have a homozygous recessive genotype.

Scroll down. You will see that there are two slightly different interactives here. Have a play, see what you learn, it is fun. 😁