A punnett square is what you use in science when trying to find out what percent chance a child has of receiving a certain trait from its parents. It is just a type of chart that you can use to do this. Here is an example of how you would use a punnett square...
For example, if the father is hybrid for dark hair (dominant trait) and the mother has light hair (recessive trait) then you can use a punnett square to find out what percent chance their child has of receiving either trait. You put the mother's genotype on top represented by two little "a"s, and the fathers genotype on the side represented by a big "D" and a little "d". Then you bring the two cross and down the punnett square, and if there is a big letter you always put it first. So when you do this with those two genotypes you get "Dd" in the upper left quadrant, "Dd" in the upper right, and "dd" in the lower left and the lower right quadrants. that way you know that it is a fifty-fifty chance that the child of those two parents is going to have dark or light hair. The example on the right is not of the exact cross that I explained, but it does show how a punnett square works. So now you should understand how to use a punnett square.
For example, if the father is hybrid for dark hair (dominant trait) and the mother has light hair (recessive trait) then you can use a punnett square to find out what percent chance their child has of receiving either trait. You put the mother's genotype on top represented by two little "a"s, and the fathers genotype on the side represented by a big "D" and a little "d". Then you bring the two cross and down the punnett square, and if there is a big letter you always put it first. So when you do this with those two genotypes you get "Dd" in the upper left quadrant, "Dd" in the upper right, and "dd" in the lower left and the lower right quadrants. that way you know that it is a fifty-fifty chance that the child of those two parents is going to have dark or light hair. The example on the right is not of the exact cross that I explained, but it does show how a punnett square works. So now you should understand how to use a punnett square.
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