Paleobio Home Cassit Birds: Lessons on Genes, Inheritance,and Evolution
Written by Jennifer A. Collins
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Please note, that the following lessons are still in draft format. A finalized version will be up sometime in the future.

Lesson One: Students study a family of Cassit birds and recognize distinguishing features that have been inherited. They then learn that these features (phenotypes) are coded for in the DNA of the birds as genes on chromosomes.

Lesson Two: Students use their understanding of genotype and phenotype to create their own Cassit bird by flipping pennies to represent genes. The class records the genotype and phenotypes of the birds produced so that a data table and graph can be started. This information will show students how genotypic and phenotypic frequencies change.

Lesson Three: Students identify that gametes have only one copy of each chromosome compared to the two copies found in somatic cells. To understand how phenotypes of offspring are determined, students are given their own gamete with genes labeled. They simulate fertilization by finding a "mate" and determine the genotype and phenotype of the offspring produced. Students then use their understanding of sexual reproduction to create possible gametes for their own Cassit Bird, and mate them with that of another classmate to produce two offspring. These birds become part of the F1 generation. After graphing this new data, students can see how the population has changed in gene and phenotype frequency. This is repeated for several generations.

Lesson Four: Students use their Cassit population to simulate how natural selection or other mechanisms can affect a population over time by "killing off" birds with particular features so that they can no longer pass on their genetic material. Students simulate and discuss how this can lead to speciation/evolution.

The objectives of this lesson are to teach students:

  • how to recognize inheritable features;
  • how to distinguish between genotype and phenotypes;
  • how features are passed on from generation to generation;
  • how populations change from generation to generation;
  • how natural selection, and other pressures affect the population over time.

    Time: 3-4 50 minute classes

    Grouping: individual, partners, class

  • ©   Updated: June 2003   Contact: jen-AT-paleobio or allen-AT-paleobio