Miss Matthews
12/10/09
Genetics
Overall Goal: Understand how to use a Punnett square and understand the meanings behind it.
Alabama Course of Study Objectives:
Apply Mendel’s law to determine phenotypic and genotypic probabilities of offspring.
 Defining important genetic terms, including dihybrid cross, monohybrid cross,
phenotype, genotype, homozygous, heterozygous, dominant trait, recessive trait,
incomplete dominance, codominance, and allele
 Calculating genotypic and phenotypic percentages and ratios using a Punnett
square
Class opening: Review prior lesson on dominant and recessive traits
Lesson Procedure:
 SmartBoard will be used to show students how homozygous and heterozygous
individuals are represented with letters.
 SmartBoard will be used to show students how a Punnett square is used in monohybrid
crosses. Examples will be done three to four times to familiarize the students with the
procedure.
 A class handout will be passed out containing ten problems. The first five (which contain
monohybrid crosses) will be assigned to be worked over the next ten minutes. After the
elapsed ten minutes, the students will be randomly called to work their problems at the
SmartBoard.
 SmartBoard will be used to show students how a Punnett square is used in dihybrid
crosses. Examples will be done three to four times to familiarize the students with the
procedure.
 The remaining five problems will be assigned to the students over the next ten minutes.
After the elapsed time students will be randomly called to work their problems at the
SmartBoard.
Questions: What is a monohybrid cross? What is a dihybrid cross? What percentages
(phenotypically and genotypically) will you receive in monohybrid and dihybrid crosses? Do
these percentages correspond?
Formative assessment:
 A brief discussion about the meaning of monohybrid, dihybrid, and how genotype
and phenotype percentages are obtained.
 A four question quiz containing two monohybrid and two dihybrid punnett square
problems.
Closure: The definition of monohybrid cross and dihybrid cross has been clearly defined. The
students have also learned how to calculate genotype and phenotype percentages.
Materials and Equipment:
 SmartBoard
 10 practice problems for the SmartBoard presentation
 Handouts for class
 Quizzes for class
Approximate timings for the part of the lesson:
 Class Opening: 10 minutes
 Lesson Procedure:
1. 5 minutes
2. 12 minutes
3. 12 minutes
4. 12 minutes
5. 20 minutes
 Formative Assessment: 15 minutes