Natural Selection

Objectives

In this lesson, students will learn that natural selection is based on the principle that those who are more suited to the environment are more likely to survive and reproduce. Students will:

explain how natural selection leads to changes in the characteristics of species.
conduct a lab activity to simulate natural selection.
recognize the importance of adaptations for survival.

Essential Questions

Vocabulary

Adaptation: A change in an organism over time that helps it to survive in its environment.
Biodiversity: The variety and complexity of life on Earth.
Camouflage: Appearance that is designed for hiding in the environment.
Competition: Living things striving for food, living space, mates, and other resources.
Evolution: The process whereby new species arise from earlier species by accumulated changes. Often referred to as “descent with modification.”
Fitness: The ability of a living thing to survive and reproduce in its environment.
Natural Selection: The process by which individuals in a population inherit genes that allow them to survive and be reproductively successful.
Variation: Differences in individual living things from each other.

Duration

90–135 minutes/2–3 class periods

Prerequisite Skills

Prerequisite Skills haven't been entered into the lesson plan.

Materials

Natural Selection Notes (S-8-3-1_Natural Selection Notes.docx)
Natural and Selective breeding (S-8-3-1_Peppered Moth Article.docx); available at http://geneticsevolution.suite101.com/article.cfm/natural_and_artificial_selection
Peppered Moth Worksheet (S-8-3-1_Peppered Moth Worksheet and KEY.docx)
Natural Selection in Peppered Moths (S-8-3-1_Episodic Organizer.docx)
Natural Selection Lab Activity (S-8-3-1_Natural Selection Lab Activity and KEY.docx)
hole punch
newspaper
paper cup
sheet of white paper
forceps
stopwatch/clock with second hand

Related Unit and Lesson Plans

Related Materials & Resources

The possible inclusion of commercial websites below is not an implied endorsement of their products, which are not free, and are not required for this lesson plan.

Natural and Artificial Selection; Mechanism of Evolution: Biological Change in Wild and Domestic Animals
http://geneticsevolution.suite101.com/article.cfm/natural_and_artificial_selection

What Evolution is NO
www.indiana.edu/~ensiweb/lessons/ev.not.html

Formative Assessment

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- Assess students’ understanding orally as the whole class develops the episodic organizer.
- Collect and assess the Peppered Moth Worksheet, including students’ paragraphs from question 6.
- Observe the data chart for accuracy and individual assessment.
- Observe the natural selection lab activity for student participation and comprehension.
- Conduct student conferences to review the conclusion section of the lab activity.

Suggested Instructional Supports

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Scaffolding, Active Engagement, Modeling, Explicit Instruction

W:	In this lesson, students receive explicit instruction about natural selection and read about the peppered moth as a specific example of natural selection. The lab activity in Part 2 is a simulation of natural selection and reinforces concepts from Part 1.
H:	Students learn basic principles of natural selection and then read about the story of the peppered moth.
E:	Students complete a lab activity that serves as an example of natural selection. In this way, content from the direct instruction will become more real.
R:	During Part 1, students reflect on the reading as they answer questions, create an episodic organizer, and write a paragraph. In Part 2, students reflect on their observations and data from the lab activity as they answer the analysis and conclusions questions.
E:	Students express their understandings by writing a paragraph about natural selection in the peppered moth, and by writing a conclusion about how the lab activity relates to natural selection.
T:	This lesson can be tailored by using reading and pre-writing strategies. Several strategies are suggested in the Extension section.
O:	The lesson is organized such that it begins with explicit instruction, and then moves to a whole-class activity and guided independent practice. The second part of the lesson is a lab simulation to reinforce content and provide further understanding of the mechanism of natural selection.

Instructional Procedures

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Part 1: Natural Selection and the Peppered Moth (2 days)

Explain to students that natural selection is the way that evolution happens. It is the process in nature by which the organisms that are best adapted to their environment tend to survive and transmit their genetic characteristics to the next generation. Individuals less adapted to their environments are not as likely to survive and reproduce.

Display the Natural Selection Notes (S-8-3-1_Natural Selection Notes.docx). Explain the basic concepts of natural selection. Have students write the vocabulary definitions and basic concepts in their notes. Be sure to explain that genetic variation is important because without it, populations cannot evolve.

Have students read “Natural and Selective Breeding” (S-8-3-1_Peppered Moth Article.docx).

Then, as a whole class activity, create an episodic organizer on the board that sequences the events in the peppered moth story, during the time of the Industrial Revolution. Have students volunteer answers and record those on the board. If students miss important events, prompt them with guiding questions. Refer to the Peppered Moth Episodic Organizer for an example (S-8-3-1_Episodic Organizer.docx).

Then, have students answer the questions on the Peppered Moth Worksheet (S-8-3-1_Peppered Moth Worksheet and KEY.docx). Allow time for them to plan the paragraph for question 6 and write it.

Close the class by having each student write about one other insect with an adaptation that increases its ability to survive in its environment (e.g., wasps are able to sting, so it is more difficult for predators to eat them).

Part 2: Natural Selection Lab Activity (1 day)

To prepare, gather materials for each group. You can save class time by punching holes before class and placing each group’s set of circles in a sealable plastic bag.

Begin the lesson by reviewing the peppered moth story and relating it to natural selection. Ask students, “What adaptation best helped the peppered moths to survive during the Industrial Revolution?” (Dark-colored peppered moths were able to hide against dark tree bark to escape from predators.)

Divide students into small groups and have them clear off their desks. Hand out the worksheet and materials for the Natural Selection Lab Activity (S-8-3-1_Natural Selection Lab Activity and KEY.docx). Read through the procedure aloud with students and answer any questions that arise. Have students do the activity. Circulate around the room and check that students are following the steps of the procedure. Have students clean up and return the lab materials.

Conclude the lesson by asking students to explain their results from the lab activity.

Extension:
- Students who might be going beyond the standards can create a few more steps in the episodic organizer to continue the story of the peppered moth up to the present day.
- Students who may need opportunities for additional learning can employ reading strategies such as highlighting difficult vocabulary, taking notes in the margins, or partner reading. Also, have students write an outline to prepare for writing the paragraph in Part 1. During Part 2, demonstrate the lab procedure as you read through the steps. It may be helpful to verbally accept students’ responses to the lab questions.
- Students can create a flyer that informs people of the impact that antibiotics have on the offspring of bacteria. The flyer must include:
o   Antibiotics kill most bacteria, but some bacteria survive.

o   Of those bacteria that survive, their resistant trait is passed on to their offspring.

o   A different antibiotic may then have to be used.

Research and provide an example of the resistance of insects to insecticides as a natural selection at work.

Natural Selection