Natural Selection: Facilitating Student Discussion

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Objective

SWBAT participate in discussion groups to explore how natural selection may lead to increases or decreases of specific traits in populations over time.

Big Idea

Through various discussion activities students use an inquiry approach to come to a mutual understanding of evolution by natural selection.

Engage

10 minutes

To engage students in the lesson, I show students the cartoon below.

I pose the following question to the group

"What is the message this cartoon is trying to communicate?"

To facilitate the discussion I have students participate in a RoundTable.

Procedure for Roundtable

In teams, students take turns generating written responses, solving problems, or making a contribution to the team project.

  1. Students sit in teams of four.
  2. Each student takes a turn writing an answer to posed question on paper passed around the group. 
  3. Teams are given 5 minutes to complete 1 round table.
  4. Teams then share out answer to whole group.

Teacher Note:  Depending on your students, you may want to white out text under each picture since it gives away the answer.  I use this strategy as a formative assessment probe to see if students still have misconceptions that individuals can intentionally adapt to their environment. My Adaptations and Evolution of Populations lesson addresses this misconception.

Explore - Student Discussion

40 minutes

In this section of lesson students explore the necessary conditions for evolution by natural selection by completing a Natural Selection Activity.  This activity is adapted from the University of California, Los Angeles Life Sciences 1 Demonstration Manual Copyright 2013 by Drs. Jennifer Doherty and Ingrid Waldron, Department of Biology, University of Pennsylvania.

Activate: As my students are nature deprived, I feel it is important that I provide context. Today I use The Making of the Fittest, an HHMI video. You may want to preteach "visual predator". Rather than telling students, you could ask them what some of the ways are that hunters can detect their prey.


Directions:

1.  Students begin exploring the relationship between adaptation and fitness through inquiry based problems that require higher order level thinking skills through application and analysis of data. (MS-LS4-6 -Use mathematical representations to support explanations of how natural selection may lead to increases and decreases of specific traits in populations over time.)

In this particular exercise students have a discussion to identify what mouse has the most fitness based on the definition given, ability to survive and reproduce. To facilitate this peer discussion I have students practice Turn to Your Neighbor. (Teacher Notes:  The correct answer is the Tan mouse since it reproduce the most number of pups).

In Turn to Your Neighbor students consider a problem or question for a few minutes, then discuss it with the person next to them. After a few minutes, several pairs share their ideas with the class. Also called "think-pair-share", this strategy promotes the exchange of ideas and helps students clarify points or apply concepts to a problem or situation. (SL7.1 - Engage effectively in a range of collaborative discussions (one-on-one, in groups, teacher-led) with diverse partners on grade 6 topics, texts, and issues, building on others’ ideas and expressing their own clearly.)  

 

2.  In problem 3 of the Natural Selection Activity students delve deeper into a more complete definition of fitness, the ability to survive and reproduce offspring who can survive and reproduce. (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.  

 It's important to realize that reproduction only provides fitness if those young are able to grow up to adulthood reproduce themselves.  If young die before they reach reproductive age there is no way to continue the passing of genes to future generations.  In this problem students are presented with data from four different lions and are required to choose lion that they believe to be the most fit based on the new more complete definition.  For this problem I have students participate in Corners. This strategy is explained in my reflection.

 

3.  In problem 6 of the Natural Selection Activity students analyze a series of pictures that show natural selection in a population of cacti. (CCC - Cause and Effect)  Students are required to explain how these pictures illustrate the three necessary conditions for evolution by natural selection.  To facilitate this small group discussion I have students practice Simultaneous Round Table.

Using Simultaneous Round Table student teams simultaneously generate responses, then pass their list or product clockwise so each teammate can add to the prior responses.  (SL7.1 - Engage effectively in a range of collaborative discussions (one-on-one, in groups, teacher-led) with diverse partners on grade 6 topics, texts, and issues, building on others’ ideas and expressing their own clearly.)

  1. Teacher assigns a topic or question. (see problem 6)

  2. All four students respond simultaneously by writing or drawing.

  3. Teacher signals time, or students place papers/pens down thumbs up

    when done with the problem.

  4. Students pass papers one person clockwise.

  5. Students continue writing or drawing, adding to what was already on

    the paper.  

Evaluate

10 minutes

I close the lesson with an Exit Slip, which summarizes what students have learned in this lesson's activities.  I use this exit slip as a summative assessment in terms of content. 

In addition I have students complete a Two-Minute paper on their learning experience.  I want to know if student discussion strategies aided them in their learning. A Two-minute Paper is a quick and simple way to collect feedback from students about their learning at the end of an activity, field trip, lecture, video, or other type of learning experience.  Students are given two minutes to respond to a predetermined prompt in writing.