Monohybrid Cross

Monohybrid cross is a really simple idea, simply take a sqaure and label all the sides with letters, which in most cases (A) means dominant trait while (a) refers to the recessive trait then you simply "multiply" them putting the terms together in the respective boxes of the sqaure and there you go, theres your genetic and phenotypic ratios.

Genotypic ratios: 1AA: 2Aa: 1aa
Phenotypic ratios: 3 dominants: 1 recessive