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11C Constancy and Change #2
Things change in steady, repetitive, or irregular ways or sometimes in more than one way at the same time....
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Biological Clocks
Purpose
To challenge students to document patterns of change in the context of biological/internal clocks.
Context
In earlier grades, students have learned that some things change, things can change in different ways, people can measure some change, and some changes are hard to see. (Benchmarks for Science Literacy, p. 272.) Now students are ready to record patterns of change by using tables or making graphs.
One way students can begin to identify patterns of change is by learning about biological/internal clocks. The concept of internal clocks refers to the biological rhythms of our bodies and other animals' bodies. These rhythms work like clocks to signal different things. For example, we feel hungry for meals around the same time each day, we are ready to wake up at approximately the same time each morning, and ready for sleep at our usual bedtime. You can also think about migrating birds. How do they know when it is time to migrate? How does a bear know when to hibernate? How does a flower know when to bloom? These are questions that involve a "biological clock" that signals through the body the time to do a particular thing.
This lesson will challenge students to consider the idea of biological clocks. By first observing the opening and closing of a Morning Glory flower, students will be introduced to the concept of biological clocks in a tangible, hands-on way. You will then lead them to identify internal clues they experience at different times of the day and talk about their own biological clocks.
Planning Ahead
Materials (adapted from the Science Museum of Virginia activity):
- 1 clock
- 1 Morning Glory flower
- Several magazines
- Construction paper
- Glue
- Scissors
- Crayons
- Clock: Student Handout Sheet, page 7, from Can Plants Tell Time? A Classroom Activity
Other Materials:
Motivation
Students are familiar with flowers, but many have never seen a flower actually open and close. Bring a Morning Glory flower into the classroom. (You can purchase a Morning Glory flower at a garden shop or grow one from seed.) This flower will be closed when students arrive for the day, but it should open around 10:00 a.m. and will remain open until evening. Witnessing this opening will probably be exciting to students and they will be filled with questions about why this happens.
Can Plants Tell Time? A Classroom Activity will give you a good foundation for teaching about biological clocks and the classroom activity is a good one for getting students excited about this concept. The lesson includes excellent questions to help you lead a class discussion under the section, "Getting Started." Because you will spend additional time developing another activity in the next section of this lesson, you may want a shorter version of the Morning Glory activity.
After students have had a chance to watch the classroom's Morning Glory open, give them the sheet entitled, Clock: Student Handout Sheet (page 7, from Can Plants Tell Time? A Classroom Activity). As described in the online lesson, they can color their clock and glue pictures of other flowers or animals around it. You are introducing them to the idea that living things have biological clocks.
Development
Now that students are intrigued by the idea of biological clocks and have had a chance to talk about their excitement and ask questions, they are ready to think about the biological clocks people have. Ask students to think about things they experience each day around the same time each day. Because this is such a complicated concept, most students will need help thinking about this.
To get them started, you can ask them questions like:
- Are there certain times of the day that you get hungry?
- Do you feel sleepy around the same time each night?
- Can you tell when it is time for recess, even if you have not looked at the clock?
- If there were no clocks, do you think you would still do things at the same time each day? Discuss.
Questions like these will help students think about their own internal clocks. Tick-Tock: Biological Clock, on the Journey North website, is helpful for encouraging students to think about their own biological clocks. This site suggests five student activities. While this lesson will utilize the first activity suggested, reviewing all five will give you a range of ideas to use with your particular group.
For students at the older range of the 3-5 grade level, the first activity on this site may work well as it is written. For younger students, you may need to approach the idea of this activity without asking students to guess a specific time. You can still cover the clocks, but instead of choosing random times throughout the day to ask them for internal cues, ask them questions at particular times.
For example:
- Right before lunch time, ask, "How are you feeling physically?" You may need to ask some additional questions to help them identify the sensation of hunger.
- Before recess, ask them, "What do you think we usually do right now?" Discuss how they may feel like jumping and running around, versus feeling sleepy.
If you also want to ask them about external cues, you could ask them things like:
- When the school bell rings, what does that tell us?
- Does it ring at this same time every day?
- Does it always signal the same thing?
- When is it the most noisy in the hallway?
- When do we see buses parked outside the school?
In discussing these ideas with students, you can help them recognize that there are sensations we feel through our body that signal certain things (biological clocks). There are also things we hear, see, and smell around us that tell us it is time for something.
Students are now ready to document their biological clock signals. Cover all classroom clocks and ask students to put their watches away. Let them know that they will do an experiment for the week. The class will try to guess what time it is without the help of clocks! Give students the My Biological Clock student sheet. They will document the time they think it is and record their internal/external cues on this table for four days.
Remember that students may need some help in identifying cues, especially bodily signals. You can expect that some students will identify mostly external cues for the specified times of day. Students have had more practice with remembering daily schedules than with reflecting upon internal cues. Some students may guess that recess is at 1:00 because they know it always follows their 12:30 lunch time. Others may connect lunch time with the ending of math class. You may need to help students look for additional signals for these times. Help them think about the feeling of hunger, fatigue, excitement, or other bodily cues you think they may experience in relationship to these times of day. It might be helpful for the class to share the kinds of information they recorded after the first day. This will give students additional ideas about the kinds of cues that signal things for us and provide a good opportunity for discussing the idea of internal cues more if it seems students are still struggling with this concept.
As students begin filling out their tables, you can help them make sense of their information by talking with them about what they are recording.
For example, you can make observatory comments like:
- I see that around lunch time, you describe feeling your stomach growl.
- I see that for two days in a row, you guessed that recess time was at 1:00.
- I see that you described feeling excited when it was your favorite part of the day.
- I see that for all four days, you noticed you felt tired at dismissal time.
- What do you notice about your information so far?
With comments like these, you can guide students in recognizing the patterns that are emerging from their data. You also will be helping them understand that for each designated time of day, they have corresponding internal cues.
Assessment
Give each student the How My Biological Clock Kept Time student sheet. This worksheet is a table they can use to help them recognize any patterns that emerged from this activity.
In addition to discussing the questions at the bottom of the student sheet, you can help students look for patterns by asking questions like:
- When you look at the times you guessed for lunch, recess, etc., what do you notice?
- If you look at your first worksheet, what do you notice about the cues you recorded?
- What do the times and the cues have to do with each other?
- Do you think you would have noticed these cues or tried to guess the time if you had clocks to look at this week?
- The clock can tell us when it is lunch time. Do you think the clock helps us know when we are hungry?
While these types of questions will help students reflect on patterns of change, it is also useful to assess how well they now understand the concept of biological clocks. Lead a class discussion around the kinds of internal cues students described on their first table. Compare these to external cues.
Ask questions like:
- Which cues are more reliable?
- Which cues are easier to notice?
- Do you think clocks are set to these bodily signals that people experience at certain times every day, or do we feel these things because the clock tells us a certain time?
These kinds of questions will help students really focus on the idea of biological clocks.
To give students another form of reflection, ask them to write a short essay about biological clocks. Their essays should include the information from their tables as well as a statement about what they learned from this project. Tables are good scientific tools. In this case, they provided a place for students to record, organize, and analyze their information. Tables also tell stories. Writing an essay that describes their tables is a good way for students to practice translating their data into scientific statements. You will also be able to get a better idea of how students now understand the concept of biological clocks and how they are able to recognize patterns of change with their tables.
Extensions
If students ask questions about biological clocks that yield succinct, quantitative answers (all answers fit into two or three categories), then students can graph their data as well. For this level, graphs should be kept simple. Vertical bar graphs are the most meaningful visual display of information for young children. The most important aspect of graphing for this age is helping children view their data from a different perspective but in a way that helps them tell a story about their data. (Benchmarks for Science Literacy, p. 271.)
It may also be fun for students to make some predictions about behavior (people, plant, or animal) based on their biological clocks. For example, they can follow a particular concept through the school year and the changing of seasons. Again, making tables and graphs is a meaningful scientific way to record and analyze data.
Students could try relying on their internal clocks to wake up in the morning, rather than on alarm clocks or family members. They could record their wake-up times for a week and compare them to what they usually are with help from their alarm clocks or family members. This could lead into a discussion about their internal clocks.
You could revisit Can Plants Tell Time? A Classroom Activity to get ideas about other flowers that open and close at regular times. The class could have fun planting their own!
Discuss migrating and hibernating animals. The Tick-Tock: Biological Clock page on the Journey North site offers many in-depth articles and activity ideas about specific animals.
Created : 08/05/2002 |