Recently, seventh grade students have been studying biological inheritance and genetics. They have followed a horse pedigree, completed gene surveys and are currently creating aliens based on Punnett squares. The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype.