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The Best of the Best

Darwinian Fitness

K20 Center, Alexandra Parsons, Tiamber Derrick | Published: May 7th, 2025 by K20 Center

  • Grade Level Grade Level 8th, 9th, 10th, 11th, 12th
  • Subject Subject Science
  • Course Course Biology I
  • Time Frame Time Frame 2-3 class period(s)
  • Duration More 95 minutes

Summary

This lesson is intended to be either an introduction or a refresher of Darwinian fitness. Students think about what it means to be 'fit' and the impact humans have had on this natural mechanism.

Essential Question(s)

Why is biological fitness such a difficult concept to describe?

Snapshot

Engage

Students examine and discuss their prior knowledge about fitness.

Explore

Students complete the Mice Living in a Desert activity to gain a more in-depth working definition of fitness.

Explain

After a class discussion about Darwin's five factors that influence survival, students identify evidence of the factors from the Mice Living in a Desert activity.

Extend

Students read a story about Frog Evolution in Chernobyl and discuss how the story shows evidence of each factor that influences survival.

Evaluate

Students create a cartoon to illustrate their understanding of the Frog Evolution story or another example in nature that shows how the five factors influence survival in an organism. Students provide a final definition of fitness based on evidence from the reading or research from the real-world example and share out with the class.

Materials

  • Lesson Slides (attached)

  • Four Corners Signs (attached; one per teacher)

  • Mice Living in a Desert handout (attached; one half page per student)

  • Frog Evolution Article (attached; one per student)

  • The Peppered-Moth (attached; optional)

Engage

Use the attached Lesson Slides to introduce the lesson. Use slides 2-4 to go over the topic, learning objectives, and the essential question. Show slide 5, which contains different student statements about fitness. Tell students to read the statements, and then move around the room to the "corner" with the name of the student whose definition of 'survival of the fittest' they agree with the most.

Once the students have chosen a corner, have them talk with others at that corner to build an 'argument' of why the statement they chose is the best. Have each group share its argument.

Explore

20 Minute(s)

Show slide 6, which includes pictures of a variety of animals. Have the students answer the questions on the slide. What makes the animals special? What is 'useful' about what makes them special? Ask students to share their thoughts with a partner before sharing with the whole class.

Show slide 7, this shows the same pictures as the previous slide but now the question is about which animals fit with their original definition of “fitness.” Ask students to write down which animals fit their definition, which ones don’t, and why.

Once they're done thinking of answers, move to slide 8. Have them think back on how they defined the term "survival of the fittest" in the Engage section. Have students create an Example Non-Example chart in their notes. Have them list each animal that supports that definition as an example and each animal that doesn't support that definition as a non-example. Just like the Engage activity, try not to get hung up on every detail being exactly right. Let students go on the full journey instead of expecting them to reach the end immediately.

Explain

25 Minute(s)

Move to slide 9. Pass out the Mice Living in a Desert activity to each student. Allow them to work in groups of two or three and allow them about 20 minutes to answer the questions.

Start with talking about the last question of the handout (which references the four definitions of fitness again). Have students share their answers in a way that is comfortable to you and your class.

Extend

30 Minute(s)

Pass out the Frog Evolution Article from Science Journal for Kids and Teens.

Show slide 10 have students read the article and use the Why-Lighting strategy as they read.

  • Prompting question: "What is the human influence on Darwinian fitness?"

  • Highlight phrases within the article that contribute to answer the question.

  • Write in the margins why you highlighted that phrase.

Why-lighting may not come naturally to students, so modeling how to do why-lighting with the whole class for the first 1-2 paragraphs may be beneficial. As you model, ask students to consider what makes a “good” note? Did we highlight something that helps us answer the question? Give them time to continue why-lighting on their own or with a partner. After students are done, have them jot all of their margin justifications on a sheet of paper.

Show slide 11. From their margin writings, ask students to put together a PSA (Public Service Announcement) Cognitive Comic about how animals or organisms are influenced by humans, for good and for bad.

Tell students:

  • There needs to be a message, but this is also a comic so see if you can add in some laughs

  • This is a great time to reflect on how good your margin notes were. What was helpful and what was hurtful toward making your comic?

  • How will your illustrations help with the message? They need to be more than just a person standing there talking.

When students have completed their comics, post their work around the room (or in the hall) for everyone to see.

Evaluate

10 Minute(s)

Show slide 12, which asks students to reflect on their learning using a modified Metacognitive Cards strategy. For a template of metacognitive cards, go to the instructional strategy card. Stress to the students that they are reflecting on how they learned, not what they learned. Have them put this reflection in their notebook so that they can revisit it the next time you do a similar activity or the next time you ask them to reflect on their metacognition.

Resources

Publisher

K20 Center

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Standards

ACT College and Career Readiness Standards - Science (6-12)
IOD201: Select one piece of data from a simple data presentation (e.g., a simple food web diagram)
SIN303: Find basic information in text that describes a complex experiment
EMI603: Use new information to make a prediction based on a model
Next Generation Science Standards (Grades 6, 7, 8)
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.
Next Generation Science Standards (Grades 9, 10, 11, 12)
HS-LS4-2: Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.
Oklahoma Academic Standards (8th Grade)
8.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.
8.LS4.4.1: Natural selection leads to the predominance of certain traits in a population, and the suppression of others.
Oklahoma Academic Standards (Biology)
B.LS4.2 : Construct an explanation based on evidence that biological diversity is influenced by (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.
B.LS4.2.1: Natural selection occurs only if there is both (1) variation in the genetic information between organisms in a population and (2)variation in the expression of that genetic information—that is, trait variation—that leads to differences in performance among individuals.

Facilitator Resources

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  • Four Corners Signs–The Best of the Best
  • Lesson Slides—The Best of the Best

Learner Handouts

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  • Frog Evolution Article—The Best of the Best
    • English
    • Spanish
  • Mice Living in a Desert Explore—The Best of the Best
  • The Peppered Moth Story—The Best of the Best

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