Woodworms: A study of natural selection

A study of natural selection and the evolutionary process through the use of a fictitious species, toothus pickii.

A lesson plan for grades 9–12 Science

By B. Carl Rush

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Related topics

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Learning outcomes

1. Students should be able to identify adaptations within a species and the benefits of each.
2. Students should be able to identify environmental factors affecting the success of individuals within a population.
3. Students should be able to follow the success or failure of different phenotypes according to collected data.
4. Students should be able to successfully graph data collected in the field.

Teacher planning

Time required for lesson

1 hour

Materials/resources

• fifty red toothpicks (number of toothpicks may be adjusted based on class size)
• fifty yellow toothpicks
• fifty blue toothpicks
• fifty green toothpicks
• handout describing the exercise for students

Technology resources

optional: computer with spreadsheet program (ex. Microsoft Excel) or graphing calculator

Pre-activities

This lesson is best used as an inquiry based introduction to natural selection. Therefore, no pre-activities are necessary. A suitable outdoor environment should be identified prior to the lab.

Activities

1. Randomly throw all toothpicks throughout a predetermined area (dramatic “summoning” of creatures from the ground is particularly effective). Larger class size dictates a larger area.
2. Students are then allowed one minute to hunt for the “woodworms”.
3. Students determine the number of each color toothpick collected and record that data in an appropriate table.
4. Students may calculate the percentage of each color caught during the hunt.
5. Graph the data (bar graph—phenotype on x and number caught on y)
6. Discuss the success of each phenotype and the environmental factors affecting each. In what situations would failing phenotypes succeed? What causes populations to change over time? How have humans affected these processes in other species?
7. For more advanced discussions, genotypes may be assigned to each subspecies and related to the phenotype. Students could determine the success of future generations of woodworms, following the resulting genotypes and phenotypes.

Alternate lesson:

For indoor use, this lesson can be modified by using hole-punched construction paper holes for the four subspecies. The colored dots can be placed on simulated grass or green construction paper or just about any substrate.

Assessment

• Data charts and graphs are graded as a lab grade.
• Class discussions are monitored for student understanding.