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Pom-Pom Natural Selection
High School
Concepts
Lesson Abstract
Students first model natural selection in a hands-on lab using 3 different colors of pom-poms on a background matching one of the colors. They proceed to run trials in an AgentSheets computer model of the same lab, and compare the results. Finally, students modify the computer model and again compare their results. Discussion questions require students to evaluate all three versions in relation to the concept of natural selection and to the role of probability and of performing multiple trials in an experiment.
Standards Addressed
SCHS-S1C1 PO 3. Formulate a testable hypothesis.
SCHS-S1C2 PO 5. Record observations, notes, sketches, questions, and ideas using tools such as journals, charts, graphs, and computers.
SCHS-S1C3 PO 2. Evaluate whether investigational data support or do not support the proposed hypothesis.
SCHS-S1C3 PO 4. Evaluate the design of an investigation to identify possible sources of procedural error, including: ⢠sample size ⢠trials ⢠controls ⢠analyses
SCHS-S1C3 PO 7. Propose further investigations based on the findings of a conducted investigation.
SCHS-S1C4 PO 4. Support conclusions with logical scientific arguments.
SCHS-S3C3 PO 2. Describe how organisms are influenced by a particular combination of biotic (living) and abiotic (nonliving) factors in an environment.
SCHS-S3C4 PO 1. Identify the following components of natural selection, which can lead to speciation: ⢠potential for a species to increase its numbers ⢠genetic variability and inheritance of offspring due to mutation and recombination of genes ⢠finite supply of resources required for life ⢠selection by the environment of those offspring better able to survive and produce offspring
Objectives
Use different types of models to demonstrate natural selection within a population.
Interpret and modify a computer model to observe effects of probability.
Key Terms
natural selection
camouflage
model
probability
trial
adaptation
population
Prerequisite Knowledge
If the topic of natural selection has not already been introduced to students, define the term for students (âthe process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do; a theory to explain the mechanism of evolutionâ) and give several real-life examples (i.e. Darwinâs finches, peppered moths, anti-bacterial-resistant bacteria). State that camouflage is the adaptation represented in these models.
If students have not worked with models, briefly brainstorm known examples (i.e. depiction of atom; a water cycle poster; an ecosystem diorama; a model airplane)
Teacher Preparation
Part I:
Copy "Pom-Pom Natural Selection Modeling Lab" from the Activity document.
Prepare materials for hands-on lab.
Parts II:
Plan for 1-2 periods of computer use.
Download and test "Pom-Pom Natural Selection Applet" for student computers.
Materials
Required Materials
Media
Equipment
Supply of green, red, and purple pom-
1 sheet of green felt or paper
student computers with access to applet (see below)
student copies of student pages from Activity document (see below)
Share the objectives and define "natural selection", and "model". Review or provide background knowledge as needed (see "Prerequisite knowledge")
Physical Modeling and Measurement
40-50 minutes
1) Pass out Pom-Pom Natural Selection Modeling Lab" packet. 2) With the help of a student volunteer, demonstrate steps 1-4 of the procedure for Part I: Hands-on Model. 3) Read steps 5-8, then direct students to get in groups, get materials, and do steps 1-8. 4) Demonstrate the beginning of the line graph, and direct students to complete steps 9 and 10. 5) The teacher and students discuss the answers, emphasizing what makes the model realistic (that pom-poms blending in with the background survive the most) and what makes the model unrealistic (pom-poms arenât alive; there are more variables involved for a living organism than just color)
Computational Modeling
20-30 minutes
1) Explain that the probabilities in the computer model they are about to use are based on common results in the hands-on lab. A review of probability may be necessary to explain why repeats of an experiment can give different results each time. Students will be able to get data from more trials than in the hands-on lab, and compare their results between the hands-on lab and computer model. 2) Orient students to the data tables for "Original Computer Model" in their packet, emphasizing that each round has only one column now, and that there are three trials instead of just one. 3) Direct students to open the "Pom-Pom Natural Selection Applet". Orient them to the following features if they have not used AgentSheets projects before: Simulation Property Editor, step, and reset. 4) If a projector is available, demonstrate steps 1 and 2 of Part II: Computer Models. Otherwise, read steps 1 and 2. 5) Direct students to do steps 1 and 2 and to then go on to steps 3 and 4.
Exploration
20-30 minutes
1) Explain that they will get to change the "death chance" of at least one color of pom-pom, but they will be comparing the results to their original hypothesis. 2) If a projector is available, demonstrate step 5. Otherwise, read step 5. 3) Direct students to complete steps 5 and 6.
Conclusion
20-30 minutes
1) Students go back to the start of their packet to review their hypothesis. 2) Direct students to answer the discussion prompts. Emphasize that prompts 1-4 require evidence from their results and that prompts 5 and 6 require their own creative thoughts.
Follow Up
120-180 minutes
Students write a formal lab report from the sections and responses in their packet. Students further explore the model by running additional trials or making further changes to the model.