Making Sense of Natural Selection

Contributor
Cynthia Passmore, Elizabeth Coleman, Jennifer Horton, and Heather Parker through NSTA The Science Teacher
Type Category
Instructional Materials
Types
Unit
Note
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.

Reviews

Description

This article from The Science Teacher magazine describes a unit of study on natural selection. Students begin by trying to explain the phenomenon of the exponential increase in a population of fish. The activities in the lessons include "Oh Deer" to teach about limiting factors and selective advantage, observations of sunflower seeds to explore variation and a "Wormeater" game for students to experience natural selection. These activities guide students as they develop a model of natural selection and then use that model to construct Darwinian explanations about how a population changes over time. The science practices are incorporated into the lessons . The article is written for high school level students, but the same approach has been used in the middle school classroom with similar results.

Intended Audience

Educator
Educational Level
  • High School
  • Grade 8
  • Grade 7
  • Grade 6
  • Middle School
Language
English
Access Restrictions

Available for purchase - The right to view, keep, and/or download material upon payment of a one-time fee.

Performance Expectations

MS-LS4-4 Construct an explanation based on evidence that describes how genetic variations of traits in a population increase some individuals’ probability of surviving and reproducing in a specific environment.

Clarification Statement: Emphasis is on using simple probability statements and proportional reasoning to construct explanations.

Assessment Boundary: none

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
The unit description is very complete about the lessons that can be used to help students develop a model of natural selection and how to help students learn to construct a Darwinian explanation. Students begin with looking at a population of fish overtime and realizing that exponential growth cannot happen forever in the natural world. There must be limiting factors. After the game of “Oh Deer” students can identify some of those limiting factors and how they might affect a population. The sunflower activity reinforces the idea of variation in a population and the Wormeater game ties together the main aspects of natural selection including selective advantage, survival, reproduction, and heredity to see how a population changes over time. A framework for writing scientific explanations in the form of a Darwinian Explanation is included so that students can make sense of their experiences.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Students argue from evidence when answering the question of why populations do not actually grow exponentially, when discussing observations of variation in living things such as sunflower seeds and survival advantages with the "Wormeater" simulation. Students engage in argumentation when critiquing other group’s Darwinian explanations. The article lists the practices that are included in each activity in a table that summarizes the lesson plan. There are descriptions in the text of the article to help teachers understand how to use the different practices in each activity. A sample discussion is included for each activity so that teachers see how the practice can be incorporated into the lesson.

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Analyzing and interpreting data is included in the sequence of activities when students observe a fish simulation to track exponential growth and participate in the simulations of Oh Deer and the Wormeater game. The article lists the practices that are included in each activity in a table that summarizes the lesson plan. There are descriptions in the text of the article to help teachers understand how to use these different practices in each activity. A sample discussion is included for each activity so that teachers see how the practice can be incorporated into the lesson.

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Students ask questions about why we are not overrun with any particular species and what happens in a simulation about deer and worm eater competition. The article lists the practices that are included in each activity in a table that summarizes the lesson plan. There are descriptions in the text of the article to help teachers understand how to use these different practices in each activity. A sample discussion is included for each activity so that teachers see how the practice can be incorporated into the lesson.

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
Students develop the model of natural selection as they tie together the phenomena of fish population growth, sunflower variation, peppered moths, deer populations and "wormeaters". They then apply the model that they have developed to explain these phenomena to tortoise carapaces found on different islands of the Galapagos. The article lists the practices that are included in each activity in a table that summarizes the lesson plan. There are descriptions in the text of the article to help teachers understand how to use these different practices in each activity. A sample discussion is included for each activity so that teachers see how the practice can be incorporated into the lesson.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
All parts of the DCI(LS4.B and LS4.C) are addressed in Observations 5-7 and Inferences 2 & 3. Other principles that are important to the DCI such as population size stability, struggle to survive and variation are addressed in Observation 1-4. Even though the article is written for a high school classroom all of the activities and pieces of the natural selection model that are discussed are very accessible for most middle level students. If vocabulary is limited when reasoning about the natural selection model, middle school students should be able to build their own model of how populations change over time. Teacher guidance and class discussions are invaluable during this part of the class. Darwinian explanations are an excellent way to help students reason with the natural selection model and should include a description of the variations in the trait in the population at some time in the past, the selective advantage, which individuals survived reproduced and passed on their genes and how the trait had changed and variations in the final population.

Crosscutting Concepts

This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.

Comments about Including the Crosscutting Concept
The article does not mention cause and effect as a cross cutting concept, but the teacher can address it when looking at the selective advantage in the scenarios described. For example, the teacher can ask about the cause of the change in the deer population in the game "Oh Deer" and then ask about its effect on the population. The same can be done with the Wormeater game and the Peppered moth example.

This resource appears to be designed to build towards this crosscutting concept, though the resource developer has not explicitly stated so.

Comments about Including the Crosscutting Concept
Students look for patterns in many of the activities, but it isn’t addressed explicitly. Teachers may want to point out the patterns that emerge from the “Oh Deer” game, the sunflower seed activity, and the wormeater game.

Resource Quality

  • Alignment to the Dimensions of the NGSS: This article was specifically written to show teachers an example of what teaching natural selection in the classroom with an NGSS approach would look like. It is three dimensional learning if teachers point out the patterns as a crosscutting concept in many of the lessons.

  • Instructional Supports: A description of the activities are included. It would be helpful to have links to some of the specific lessons such as the Wormeater game. The sequence of activities helps to provide opportunities for students to express their own ideas verbally and in written form with their models. While there are no particular suggestions to differentiate instruction for student who are English Language Learners or students with special needs, the set-up of the unit allows the teacher to provide targeted support and feedback through direct interaction with these students, and/or partnering them with peers.

  • Monitoring Student Progress: Sharing and discussing explanations for phenomena as a group and working to construct a consensus model are good formative assessment activities. Teachers can become aware of how students understand the natural selection model and can use it to explain phenomena. Misconceptions are addressed such as Lamarckian language. The summative assessment about explaining the variation of tortoise carapaces in the Galapagos will allow students to use the model that they developed to explain new phenomena.

  • Quality of Technological Interactivity: Except for the exponential growth of fish activity, there is no interactive technology involved in this lesson. The simulation might provide some problems in loading, as it requires the user to accept Java plug-ins.