Sample Sim Lesson Plan

Sample Lesson Plan: Natural Selection

This lesson plan is built around PhET's Natural Selection simulator, found here: http://phet.colorado.edu/en/simulation/natural-selection

Lesson Objective: 9^th Grade Biology:

7. The frequency of an allele in a gene pool of a population depends on many factors

and may be stable or unstable over time. As a basis for understanding this concept:

a. Students know why natural selection acts on the phenotype rather than the geno­

type of an organism.

8. Evolution is the result of genetic changes that occur in constantly changing environ­

ments. As a basis for understanding this concept:

a. Students know how natural selection determines the differential survival of

groups of organisms.

b. Students know a great diversity of species increases the chance that at least some

organisms survive major changes in the environment.

Engage: The lesson begins with a quick review of mendelian inheritance, which the students (hopefully) covered in middle school, and went over in a previous lesson in this class. The teacher draws a Punnett square on the board, asks the students to fill it out, and then asks them questions about what each square represents, the differences between genotype and phenotype, and the genotypic/phenotypic probabilities of this cross. This work can remain on the board for future reference. The most important idea here is that a trait can be present in the genotype, but not expressed in the phenotype.

Explore: During this portion, students are split into their groups of 3-4 and sent to computer stations (or, if working in a computer lab, each group of 3-4 students has access to 2 computers). To begin, the teacher passes out worksheets containing simulator instructions and demonstrates, on a computer attached to a projector, how to use the sim. After five minutes of free experimentation, students must conduct a series of investigations into the relationships between limiting factors (wolves or food), environment, dominant and recessive alleles, and the rabbit population.

Explain: During this portion, the teacher will assign each group to explain one of the conclusions they reached from the worksheet in greater detail. Students will have five minutes with their groups to write a more thorough answer and rehearse their explanation. Then, when the class goes over these questions, the teacher will call on one of the groups assigned to answer each question. If the teacher feels their answer was missing an important detail, or if another group that worked on the same question has a unique idea, other groups can also share.

Explore: This time, students will get in the same groups, but each group will be assigned to investigate one of the following three scenarios:

-What happens to the rabbit population if the environment suddely shifts to a white tundra while Wolves are the limiting factor? Why? Explain how the population's recovery changes if white fur is a recessive, rather than a dominant, allele.

-Why are long teeth (able to gather food better) a more effective limiting factor than wolves? Test both as limiting factors to investigate.

-Find an example of a rabbit with one or more recessive mutations. Using the "family tree" function in the sim, determine the genotypes of its parents and draw a Punnet square for the cross that produced that rabbit. What happens to the rabbit population if environmentally favorable mutations are recessive, and why?

During the investigation, they will be responsible for writing a short answer conclusion and drawing a model of their observations in the form of a 2-4 panel "comic," showing how the sim changes over time.

Explain: During the previous segment, the teacher will be walking around answering questions and looking at the students' work in progress. Several groups will be called on to share their models and their explanations for what happened, using the principles of Mendellian genetics. Groups assigned to the same investigation can contribute if they got different results, and the listening groups are encouraged to give the presenters feedback and critique.

Evaluate: Two pieces of work will be evaluated: Day 1's worksheet, and Day 2's model. Day 1's worksheet will be for individual students to work on, not one-per-group, to ensure that every student is accountable for their own work. In addition, the teacher will also evaluate the presentations and presentation-prep from both days. Misconceptions or missed concepts from Day 1 can be addressed in a brief direct lecture at the beginning of Day 2, to ensure that students are all working from the same foundation of information

Extend: Students, still in their groups and working at computer stations, will be allowed to go onto the internet and investigate a case of natural selection in the real world: a major shift in the phenotypes expressed by a certain animal population, or an extinction caused by rapid environmental changes. The groups will be asked to share the examples they find; more groups will be called on depending on how much time is left.