If you were looking for a more visual, hands-on way to practice their Punnett square-solving-skills, you can use plastic eggs leftover from Easter.
Assign a genotype to each egg color, such as the following:
Blue - BB
Green - Bb
Yellow - bb
This example uses incomplete dominance - i.e. Bb appears green, not blue, as it would in a straight dominant/recessive situation.
The eggs have been mixed and matched to create various genetic crosses. For example, a blue half matched with a green half would represent BB x Bb.
Now have your students use a Punnet square to solve the cross, and then open the egg to check their work!
has a worksheet your student can use to determine the Punnett Squares and the results.
Source: Science Matters