Lesson Plan 4

NAME OF COURSE / CLASS: 10th Grade Biology

UNIT TITLE: Introduction to Genetics

LESSON TITLE: Probability and Punnett Squares (Lesson 4 of 5)

ANTICIPATED INSTRUCTIONAL TIME: The lesson should take two 50-minute class periods.

ENDURING UNDERSTANDING: Before discussing the complex patterns of inheritance involved in genetic crosses, it is important to understand how genes and alleles are passed from parents and how they determine an offspring’s genotype and phenotype. Once students understand allelic inheritance, they can predict the results of many different crosses by calculating the probability of certain traits being passed on to the next generation. While it is customary to look at one trait at a time when students are first learning about probability, eventually students can analyze the results of one cross involving multiple genes.

RATIONALE: Students need to understand how traits are passed from parent to offspring in order to understand hereditary issues. Before students can fully understand the more complicated concepts in genetics, they need to understand how inheritance happens and be able to accurately predict the results of a cross using probability and punnett squares. Probability and punnett squares help students predict the likelihood of a trait being passed on from one generation to the next. Students need a basic understanding of dominance and recessiveness in order to perform genetics problems. After the students have mastered mono and dihybrid crosses, they will have a better comprehension of how traits are passed from one generation to the next and the knowledge necessary to learn the details of some of the exceptional genetic outcomes.

G.4.1 To evaluate the relationship between probability and genetics
G.4.2 To accurately predict inheritance patterns using probability and punnett squares
G.4.3 To describe genetic crosses that do not show simple dominance
G.4.4 To apply Mendel’s principles

O.4.1 Students will demonstrate the basic principles of probability
O.4.2 Students will accurately predict progeny genotypes and phenotypes using probability
O.4.3 Students will construct punnett squares to predict progeny genotypes and phenotypes
O.4.4 Students will predict progeny genotypes and phenotypes beyond simple dominance relationships
O.4.5 Students will be able to define and apply Mendel's principles when solving genetics problems.

On day one, the material will be presented through an introductory coin toss activity, a discussion of the activity, a Power Point presentation, example problems on individual white-boards during class, and a genetics problem set assignment to be completed as homework.
On day two, the material will be presented with an introductory activity about height, a discussion of the activity, an inquiry-based exploration worksheet to be completed in groups during class, and a compiled packet of all of the information that each group discovered through their inquiry-based search.

Dogru-Atay & Tekkaya (2008) found that teaching genetics works well when the teacher uses the learning cycle. Genetics is one of the central concepts in biology, and one that connects not only to many concepts within biology but also to many other disciplines. In order for students to understand the importance of genetics and remember the information, they need to make connections from the new material to prior knowledge and real-life situations. Instead, most classroom teachers rely on rote memorization as an effective method for learning genetics. Dogru et. al. suggests that teachers implement the learning cycle to solve the discrepancy between how students learn and how teachers teach. The learning cycle is an inquiry-based teaching strategy that involves three phases: exploration, concept introduction, and concept application.


  • Science
    • 9-12.L.2.1. Students are able to predict inheritance patterns using a single allele.
    • 9-12.L.2.1A Students are able to predict to predict the results of complex inheritance patterns involving multiple alleles in genes.
  • Nature of Science
    • 9-12.N.1.2. Students are able to describe the role of observation and evidence in the development and modification of hypotheses, theories, and laws.
    • 9-12.N.2.3A. Students are able to demonstrate correct precision in measurements and calculations.
  • Mathematics
    • 9-12.S.2.1. Students are able to distinguish between experimental and theoretical probability.
    • 9-12.S.2.2. Students are able to predict outcomes of simple events using given theoretical probabilities.

  • Life Science Standard
    • 9-12 Molecular Basis of Heredity
  • History and Nature of Science Standard
    • 9-12 Science as a Human Endeavor
  • Mathematics: Data Analysis and Probability Standard
    • M1: Understand the differences among various kinds of studies and which types of inferences can legitimately be drawn from each
    • M2: Know the characteristics of well-designed studies, including the role of randomization in surveys and experiments
    • M3: Understand the meaning of measurement data and categorical data, of univariate and bivariate data, and of the term variable

1.) Why do we have to use probability in a science class? I thought it was only used in math.
2.) If we inherit our traits from our parents, why don’t I share all of their characteristics?
3.) If parents have four children, will they show the ratio of characteristics predicted by probability or punnett squares?
4.) When do we use monohybrid crosses versus dihybrid crosses??
5.) What happens when traits are not dominant or recessive?
6.) Why is Mendel’s work even important?

During day one of the lesson, I will be checking the student’s understanding by observing the class while the work on the coin toss activity and holding a class discussion after the pre-assessment activity. The students will also answer questions on their white-boards, at which point I will be looking at every student’s answers and checking for individual understanding. If students are missing several problems during this exercise, I will briefly re-explain the material.
During day two of the lesson, I will be walking around the classroom and observing students as they work through their inquiry worksheets. I will listen to their group discussions, and prompt the students as necessary. While the students present their findings from their inquiry-based search, I will listen to each group and make sure they understand the information.

Day One:

  • Computer
  • Projector
  • One coin toss activity to display on the projector screen
  • One coin per student in the class
  • Power Point on monohybrid and dihybrid crosses
  • Dry-erase kits for each student in the class (white-board, marker, eraser)
  • Genetics problem to use during class
  • Classroom white-board/ chalk-board
  • Classroom dry-erase makers/chalk
  • Review worksheet- genetics problems for each student
Day Two:
  • Projector screen
  • Adult height activity to display on the projector screen
  • Concept Maps- Mendel-one per student
  • Inquiry worksheets 1-6, enough for each student in the six different groups
  • Computers, at least enough for two per group (six groups)
  • Textbooks and extra resources for research

PARTICIPANT MATERIALS: (See Appendix C or Appendix D)
Day One:

  • Biology textbook
  • Notebook
  • Writing Utensil
  • Coin-one per student, handed out by teacher
  • Dry-erase kits- one per student, handed out by teacher
  • Review Worksheet- one per student (homework)

Day Two:

  • Biology textbook
  • Notebook
  • Writing Utensil
  • Concept Map-one per student, handed out by teacher
  • Inquiry Worksheets- numbered 1-6, one for each student in the group
  • Computers- two per group (six groups)
  • Extra resources, textbooks, pamphlets, etc.

Day One
To start the class, students will complete the coin toss activity, which is supposed to test their knowledge of probability, an important concept in genetics problems. We will discuss the results of the activity as a class, and they I will deliver a Power Point presentation as a form of notes on probability, and punnett squares with monohybrid and dihybrid crosses. Once the students understand the crosses, they should be able to apply that knowledge to several types of problems. I will check their understanding by having the students do problems on individual white boards in class. The problems will be about dominance/ recessiveness, monohybrid/ dihybrid crosses, progeny ratios, and probability. The students will complete a review worksheet as homework due the following class day to check how well each student retains the information.
Day Two
With a firm understanding of the basic crosses and progeny ratios involved in genetics, the students should be ready to move into the exceptional crosses and concepts. In order to introduce the students to the fact that not every trait is controlled by simple mechanisms, the students will complete the adult height activity at the beginning of class. We will discuss the activity to make sure that all of the students understand that real life is not as simple as the dominant, single-allele traits problems make it seem. In order to explore Mendel’s Law/ Principles, codominance, incomplete dominance, multiple alleles, polygenic traits, and how the environment and genes interact, the students will complete an inquiry worksheet on one of each of those topics. They will then share their results with the class. By the end of the class period, all of the students will have exposure to each of the concepts covered in this lesson.
(See Appendix A for lesson script)

ASSESSMENT / HOMEWORK: (See Appendix D for assignments/ homework)

Type (D,F,S)
Coin Toss Questions
G.4.1, O.4.1

Beginning of 4

Dry-Erase Board Activity
G.4.1, G.4.2, O.4.1, O.4.2, O.4.3
During 4
Review Worksheet-Punnett Squares and Probability
G.4.1, G.4.2, O.4.1, O.4.2, O.4.3
Homework after day 1 of lesson 4
Adult Height Activity
G.4.3, G.4.4, O.4.4, O.4.5
Beginning of Day 2 Lesson 4
Observations of Students During Class
G.4.3, G.4.4, O.4.4, O.4.5
During Day 2 of Lesson 4
Inquiry Worksheet
G.4.3, G.4.4, O.4.4, O.4.5
Worksheet During Day 2 of Lesson 4
Genetics Extension Problems
G.4.3, G.4.4, O.4.4, O.4.5
Homework after day 2


  • I will hand out printed Power Points for students who have trouble keeping up with notes in class.
  • I will mix difficult and easy problems during the question and answer white-board activity to ensure all students have the opportunity to answer some questions correctly
  • I will modify the homework for students who are having difficulty with the concepts, taking away some problems, providing multiple-choice questions, or making some problems easier with hints.
  • I will be available to the students before and after school to help with the problems and concepts.
  • I will make the coin toss activity of the adult height activity larger print so that students can clearly read the words on the projector.
  • I will design the groups for the inquiry activity so that students are optimally matched to avoid off-task behavior and to provide some support for students that are struggling in the class.

There are many activities that I could do in order to teach the students about probability and genetics. I could have the students calculate the probability of getting each color of m&m in a fun-size pack of m&ms. I could also have the students play with dice and do probability problems. Another cool activity that I found while researching these topics was a worksheet where the students have to fill out a traits worksheet about themselves, compare their results to the class and decide if each trait was dominant or recessive and provide possible genotypes for themselves based on their findings. That would be a real-world connection that students would probably enjoy if time permitted. There was also an activity that I found where the students constructed punnett squares from pieces of pipe cleaner and used manipulative to show the crosses in the punnett squares. There is a plethora of information about genetics and teaching genetics. The good thing is that this lesson is flexible enough to change every year and keep trying the new activities depending on the group of students.

REFLECTION / REVISION: This section will be completed after each time I deliver the lesson to continue to improve the lesson and make it as effective and engaging as possible.

Baylor College of Medicine. (2009). BioEd online. Retrieved October 1, 2009, from Teacher Resources website: http://www.bioedonline.org/

Dogru-Atay, P., & Tekkaya, C. (2008). Promoting Students' Learning in Genetics With the Learning Cycle. Journal of Experimental Education, 76(3), 259-280. Retrieved from http://search.ebscohost.com.ezproxy.usd.edu

Miller, K.R., & Levine, J.F. (2008). Biology. Upper Saddle River, NJ: Pearson Education.

Shields, Martin. (2006). Biology inquiries: Standards-based labs, assessments, and class discussions. San Francisco, CA: Wiley Publishing.

Appendix A: Lesson Script (long version)
Appendix B: Instructor Materials
Appendix C: Participant Materials
Appendix D: Assignment/Homework

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