Punnett Squares
Fill in Punnett squares for six genetic crosses, then work out the probabilities.
About this activity
Six genetic crosses, including cystic fibrosis and polydactyly. Students tap each box of the Punnett square to choose the offspring’s genotype, then pick the probability of a phenotype. Feedback explains how each box is filled and how to count the boxes for dominant and recessive features.
How to use Punnett Squares
- Punnett Squares is a free Biology activity for Years 9 to 11 that takes about 12 minutes. Try it on this page on a computer, tablet or phone: there’s nothing to download.
- In a lesson, choose Show on the board to play it together as a class.
- To set it for a class, a teacher shares it and gets a code: students type the 6-digit code at lycolearn.co.uk/join with their first name and the first letter of their surname (no accounts needed), and their scores come back to the teacher.
Students will
- Complete a Punnett square for a monohybrid cross
- Use dominant and recessive alleles to predict phenotypes
- Express outcomes as probabilities and ratios
Teaching tips
- Remind students to write the capital letter first in each box.
- Extension: if two parents have a child with cystic fibrosis, what must their genotypes be?