Variation Is Essential: How Does Variation Within a Population Affect the Survival of a Species?

Variation Is Essential: How Does Variation Within a Population Affect the Survival of a Species?


David Upegui
Science teacher
Central Falls High School
Central Falls, Rhode Island
Doctoral candidate, University of RI

A 2019 PAEMST Awardee

Lesson Feedback


This is a lesson about phenotypical variation within populations and how these differences are essential for biological evolution. Students will use a model organism (in this case, kidney beans) to explore variation patterns and subsequently connect these differences to artificial & natural selection. The NGSS’ CrossCutting Concepts and Science & Engineering Practices are embedded throughout the lesson. The NGSS Performance Expectations covered are HS-LS4-2. & HS-LS4-4.

The main learning objectives are:

  • Using a model (kidney beans) to explore the natural variations within a population.
  • Measuring differences between individuals in a population (population of beans).
  • Describing how genetic/phenotypic variation is a key part of biological evolution because it is a prerequisite for natural selection.
  • Demonstrating in which ways genetic variation is advantageous to a population because it enables some individuals to adapt to the environment while maintaining the survival of the population.

There is no specific prerequisite knowledge required prior to completing this lesson as this can be an introductory lesson (and it is flexible enough that it can be completed during different times of the curriculum). This lesson will require more than one 50-minute class period to complete. However, if students are not familiar with writing lab abstracts, this could take additional time. Also, if you chose to have students complete the advanced math component (standard deviation), then more time will surely be required.The materials required for this lesson include a Bag of dried kidney* (or any other kind of beans) beans (split into smaller bags of 50 beans), the guide-sheet, metric rulers, and graphing paper.

During the five classroom activities in this lesson students will be:

  1. Using patterns to identify different physical attributes that are measurable and that vary over the population
  2. Measuring the length of fifty beans to the nearest millimeter, in order to see variation within the patterns.
  3. Graphing and analyzing data of the beans grouped by length.
  4. Exploring patterns of variation as possible important causes for the survival of species, and
  5. Evaluating evidence about the causes and effects of variation.

Instructor Biography

I have the privilege and honor of teaching the best students in the world, the students from Central Falls High School (my high school alma mater). I also get to keep expanding my ideas as a doctoral candidate where I focus on: Evolutionary theory, Critical Pedagogy, Mixed Methodology, Science Education and Social Justice. I teach because I have come to appreciate education (especially science education) as the avenue for lasting social justice. It is when students are empowered to ask questions and demand publicly verifiable data that they begin to understand their own true potential. Like all of us, I am a teacher, a student, and a seeker.

Additional Online Resources

Understanding Evolution
This site, created by the University of California Museum of Palentology, is entitled Evolution 101 and provides the nuts and bolts about the patterns and mechanisms of evolution.

Sponsored by ENSI, the lessons provided on this site are designed to improve the teaching of evolution in high school biology courses by encouraging teachers to teach evolutionary thinking in the context of a more complete understanding of modern scientific thinking.

Understanding Race
Created by the American Anthropological Association, this site, “Race: Are We So Different”, provides resources that encourage an integrative and comprehensive
approach to the study of race and human variation.

This site, hosted by BioInteractive at the Howard Hughes Medical Institute, offers many great resources for teaching evolution - from short films to Click & Learn interactives, and from lecture series to classroom activities.

What Does It Mean to Be Human
This site, from the Smithsonian National Museum of Natural History, is entitled “What Does It Mean to Be Human” and teaches evolution through human examples.