Introduce important terminology before performing the punnett square.
Genetics use letters to represent alleles. Uppercase letters represent dominant alleles; lower case represent recessive alleles. An individual’s genotype is is expressed with one letter for each allele. An example, the gene for plant height results in tall or dwarf (short) plants. The allele for tall plant is dominant and is represented by upper case T. The allele for dwarf plant is recessive and assigned a lower case t. Possible genotypes are homozygous dominant ( TT) and heterozygous dominant (Tt) which gives a tall phenotype and homozygous recessive (tt) which presents a short phenotype.
This video provides a great overview of monohybrid and dyhybrid crosses, it may clear a lot of misconceptions that students are having.