Tick-Tock Biological Clock
How Animals Tell Time
Students enjoy discovering examples of their own biological clocks. These clocks moderate sleep and energy cycles in interesting ways. In this lesson students will explore the concept of time and their abilitiy to keep time. Then they'll consider the importance of an accurate biological clock to a migratory species.
2. On the same day, test how well students can remember how daylight changes during the course of a year. Ask them to record the following dates on a piece of paper. For each date, record the time they think the sun rises and sets: February 1, April 1, June 1, August 1, October 1, December 1. Using a calendar with sunrise and sunset data, compare these guesses to the actual amount of daylight on those days. Ask students to consider why its important for a migratory species to notice changes in photoperiod.
3. Ask all students to stand. Divide your class into groups acording to the following characteristics: Have those that usually wear a watch move to one side of the room and those that don't to the other. While staying on the same side of the room, have those that wake to an alarm move to the back. Have those that wake naturally move towards the front. If these four groups are too large for a discussion, have them break into triads or foursomes. Ask students to talk about time: What interesting experiences have they had because of oversleeping, or with jet lag or when changing to daylight savings time? Do they have pets that seem to be able to tell time? Does time seem to pass more slowly at the dentist's office or when eating dessert? What does this mean? How would life be different without clocks? Is there any correlation between these students' performance on the time-tests above and the groups they are in?
4. Have students try an experiment. During the week, have them record the number of hours of they sleep each night. On Friday, calculate the average for the week. On the weekend, have each student record the time he/she goes to sleep on Friday night and the exact time he/she wakes up on Saturday morning. Students should wake-up on their own--no alarm, no wakening by another person. How close was their wake-up time to the average number of hours of sleep they had during the past week?
5. Chose one Journey North migratory animal. What would happen if this animal were to lose track of time? Write a story about the consequences that would result. Be sure to consider all the activities the animal does according to a daily and annual cycle.