Biologists: Working with probability
In this lesson for grade six, students will use theoretical probability to predict genetic outcomes, and will understand how mathematical probability is used in biological careers.
A lesson plan for grades 6–7 Mathematics and Science
Provided by CareerStart
Learning outcomes
 Students will use theoretical probability via tree diagrams and/or Punnett squares to predict the outcome of the potential of male/female offspring and the crossing of two genes.
 Students will gain an understanding of the importance of math to careers in biology.
Teacher planning
Materials needed
 Student handouts:
 “Let’s Review”
 “Biology Rules!” (for regular students)
 “I Could be a Biologist!” (for advanced students)
 Instructor answer key
Time required for lesson
One class period
Procedure
 Review theoretical probability with the class.
 Share with students some basic background information about careers in biology:
A biologist is a scientist devoted to and producing results in biology through the study of organisms. Typically biologists study organisms and their relationship to their environment. Biologists involved in basic research attempt to discover underlying mechanisms that govern how organisms work. Biologists involved in applied research attempt to develop or improve medical, industrial or agricultural processes. Some biologists work in management positions coordinating or supervising research. Technicians perform specialized tasks using laboratory equipment.
There are many types of biologists. Some deal with the macroscopic world and other with the microscopic. There is much overlap between different fields, and it is often hard to classify a biologist as only one of them. Some of the fields are:
 Animal
 Biochemistry
 Cell
 Developmental
 Ecology
 Evolutionary
 Genetic
 Microbiology
 Molecular
Many jobs in biology as a field require an academic degree. A PhD (or equivalent) is generally required to direct independent research but a bachelor’s or master’s degree is sufficient for most nonresearch positions. Training on the undergraduate level usually is very general while later training involves a specialization in a specific area of biology.
(Source: U.S. Department of Labor’s Occupational Outlook Handbook.)
 Explain to the students that some biologists work to understand genetics. Studying genetics can be beneficial because it helps predict the likelihood (probability) of certain traits occurring, whether it is with plants, animals, or humans. A British geneticist named Reginald Punnett created his own way to determine the probability of traits occurring by making a table that looks like a tictactoe board. Today, we call the table a Punnett square. To create a Punnett square, the parents’ genotypes are listed horizontally and vertically along the borders of the square. When traits from each parent are crossed, the results are the probability of the offspring’s genotype.
 Guided practice: Walk students through example problems on “Let’s Review” handout.
 Independent practice: Have students complete handouts — “Biology Rules!” (for regular students) OR “I Could be a Biologist!” (for advanced students).
Websites

Optional resources for more information on the topics covered in this lesson
 Dog Breeding
 This PBS game challenges students to breed a certain type of puppy by selecting parents with the right traits.
 The Story of Mendel
 This website gives a brief biography of Mendel, explains his experiments in genetics, and allows students to breed their own hybrid pea plants in an interactive experiment.
 Mutant Fruit Flies
 Exploratorium explains how gene mutations occur using the example of fruit flies.
 DNA from the Beginning
 This comprehensive website by the DNA Learning Center covers 75 experiments that led to modern genetics. For each experiment, there is a written explanation of the concept, an animation to further explain, a gallery of related images, a video with an expert explaining the concept, a biography of the experimenting scientists involved in the discovery, and an interactive problem so that students can test their knowledge.
 Common Core State Standards
 Mathematics (2010)
Grade 7
 Statistics & Probability
 7.SP.8Find probabilities of compound events using organized lists, tables, tree diagrams, and simulation. Understand that, just as with simple events, the probability of a compound event is the fraction of outcomes in the sample space for which the compound...
 Statistics & Probability
 North Carolina Essential Standards
 Science (2010)
 7.L.2 Understand the relationship of the mechanisms of cellular reproduction, patterns of inheritance and external factors to potential variation among offspring. 7.L.2.1 Explain why offspring that result from sexual reproduction (fertilization and meiosis)...
North Carolina curriculum alignment
Mathematics (2004)
Grade 6
 Goal 4: Data Analysis and Probability  The learner will understand and determine probabilities.
 Objective 4.04: Determine and compare experimental and theoretical probabilities for simple and compound events.