Teaching dihybrid crosses can be challenging because it involves layering several biological concepts, like independent assortment and statistics.   This worksheet illustrates how gametes are formed from the parents and used to create a 4×4 Punnett square that is used in basic genetic problems.  

The worksheet is set up for beginner students to go through the steps to solve the problem, finally showing how the 9:3:3:1 ratio the Mendel established with his pea plants.

The trait being studies is hair color and type (curly or straight) in guinea pigs.  These traits have been simplified for the exercise, guinea pig hair is actually much more complex.

Grade Level:  7-9

Time Required:  30 minutes