Punnet squares are used to find genotypes of offspring. You can use letters to represent a genotype, but most genotypes already have there represented letters.
A punnet square is obviously shaped into a square. It is cut into fourths, and to find an offspring's genotype, you have to do the following steps. First step is to put both of the parents' genotype above two sides of the squares, which is the top side and the left side. The next step is to cross over the two genotypes. So for example, we're looking to see if two parents will have a brown-haired kid, or a blond-haired kid. Blond is the recessive, while brown is the dominant. The letter that will represent brown is "B," while the blond representative will be "b." Put the parent genotypes on the top side and the left side, so in this example, Mom's genotype will be "BB," which makes her hair brown, and the Dad's genotype will be "Bb," which also makes his hair brown. Now cross the left side genotype with the top side genotype. "Bb" is top side, and "BB" is left side. So first, cross the first "B" with the first "B" on both top and left side, which makes "BB." Write that in the punnet square. Then continue and do the same thing with both sides.
Punnet squares are really easy to use. It doesn't matter what genotype goes w
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