How many hours should be in a day? One species of drosophila naturally prefers a 24.5 hour day, while another strongly prefers a 19-hour day. An animation and graph share data from each of these species when exposed to the typical light cycle of a 24-hour day as well as to no light when they must determine their own cycles. The patterns clearly demonstrate the importance of light in combination with an internal clock to determine the ideal length of a day.

Concepts

genes, molecules

Show More Show Less

Additional Tags

science

Show More Show Less

Instructional Ideas

• Relate circadian activity in drosophilia to the human circadian rhythms and the changes by season and location
• Consider the shift in teenage humans to fall asleep well after dark and sleep through the typical morning cycle

Classroom Considerations

• Relies on prior knowledge of circadian rhythms, fruit flies, and light/dark cycles

Pros

• Links to related videos
• Provides background information on the lecture

Cons

• None

Common Core

SL.9-10.2 SL.11-12.2 RST.9-10.4 RST.11-12.4