Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
Click to return to the Evolution Home Page
darwin change extinction survival sex humans religion
Online Lessons for Teachers: Learning Evolution


How Does Evolution Work?

View LESSON 4 Student Page

Activity One: Breeding Bunnies

Activity One: Teacher Notes

Activity Two: Flashy Fish

Materials You'll Need:


Flashy Fish: Data form (pdf)


Flashy Fish: Discussion Questions (pdf)

Activity 2 Teacher Notes: Flashy Fish

I am especially interested in the interplay between evolutionary, ecological, behavioral, and genetic factors, and how they affect geographic variation and the process of natural selection in natural populations. My interests lie largely in the region of overlap between evolution, ecology, behavior, and population/quantitative genetics. As can be seen by my publications, my approach is a mixture of theory, field observations, and experimental manipulation, in both field and laboratory. I am a theoretician in that I generate most of my hypotheses and predictions, but I am also an empiricist in that I like to test my predictions as soon as they are made.  

- John Endler
(from an online biography)

Students pretend they are a scientist like John Endler in this Web activity. They visit his pools, form hypotheses, and test them out. In the process, they learn about natural selection and sexual selection.

Learning Goals


To help students understand the concept of natural selection


To help students understand the concept of sexual selection


To explain to students the interplay between selection factors in a population of guppies



Distribute, or have students print the Flashy Fish: Data form (pdf) and the Flashy Fish: Discussion Questions (pdf).


Review the major components of natural and sexual selection with the students.


Have students launch the Sex and the Single Guppy Web activity.

 Screen grab from the Web activity Sex and the Single Guppy.

Sex and the Single Guppy


Ask students to follow the instructions on the Student Page. Encourage them to conduct more than one experiment to support their hypothesis.


Use the Discussion Questions to frame a classroom discussion of the experiment. Be sure to discuss the interplay between selection factors in the population of Endler's wild guppies.

Videos Web Activities Site Guide About the Project FAQ Glossary Site Map Feedback Help Shop