Light and Sleep Lesson #1
Grade Level:
Subject:
Writer
5-8
Earth/Life Science
McGinnis, Patty
Lesson Goal
Students will use data to build their conceptual understanding that the presence and/or absence of light
is important for controlling circadian and circannual rhythms.
Objectives
Students will:



Determine the nature of circannual rhythms within organisms*
Determine the nature of circadian rhythms within organisms*
Construct an explanation of how light affects circadian rhythms
*Note: The definition of circannual rhythms is a biological cycle or rhythm with a period length of
approximately one year. The definition of circadian rhythms is a biological cycle or rhythm with a period
length of about 24 hours.
Standards Alignment
Note: This lesson does not fully meet a specific performance expectation of the Next Generation Science
Standards (NGSS) but supports student achievement of the performance expectations listed below. The
lesson is not a full unit of study; therefore you should consider how it could be incorporated into your
own unit of study.
Performance Expectations:
MS-LS1-8. Gather and synthesize information that sensory receptors respond to stimuli by
sending messages to the brain for immediate behavior or storage of memories. [Assessment
Boundary: Assessment does not include mechanisms for the transmission of this information.]
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MS-LS2-1. Analyze and interpret data to provide evidence for the effects of resource availability
on organisms and populations of organisms in an ecosystem. [Clarification Statement: Emphasis
is on cause and effect relationships between resources and growth of individual organisms and
the numbers of organisms in ecosystems during periods of abundant and scarce resources.]
Disciplinary Core Ideas:
LS1.D: Information Processing
Each sense receptor responds to different inputs (electromagnetic, mechanical, chemical),
transmitting them as signals that travel along nerve cells to the brain. The signals are then
processed in the brain, resulting in immediate behaviors or memories.
LS2.A: Interdependent Relationships in Ecosystems
Organisms, and populations of organisms, are dependent on their environmental interactions
both with other living things and with nonliving factors.
Cross-Cutting Concepts:
Cause and Effect: Cause and effect relationships may be used to predict phenomena in natural
systems.
Patterns: Patterns can be used to identify cause and effect relationships.
Graphs, charts, and images can be used to identify patterns in data.
Science and Engineering Practices:
Obtaining, Evaluating, and Communicating Information: Gather, read, and synthesize
information from multiple appropriate sources and assess the credibility, accuracy, and possible
bias of each publication and methods used, and describe how they are supported or not
supported by evidence.
Planning and Carrying Out Investigations: Conduct an investigation to produce data to serve as
the basis for evidence that meet the goals of an investigation.
Analyzing and Interpreting Data: Analyze and interpret data to provide evidence for
phenomena.
Constructing Explanations: Construct an explanation that includes qualitative or quantitative
relationships between variables that predicts and/or describes phenomena.
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Time Required
Two 40-minute periods
Materials Needed



Large whiteboards for groups OR large pieces of paper
Student sheet #1
Student access to computers, tablets, or other devices that have internet capability
Prerequisite Knowledge


Students are expected to know that from any place on Earth, the maximum height that the Sun
reaches in the sky above that place during the day gradually rises and falls during the year.
Students need a basic understanding of the seasons and day length.
Before the Lesson


Download any desired images from this lesson to a computer for projecting or print out copies
for students.
If you are unfamiliar with circadian rhythms and sleep, it is recommended that you visit “Sleep
Topics” at http://sleepfoundation.org/sleep-topics and read “The Time of Our Lives” at
http://learn.genetics.utah.edu/content/inheritance/clockgenes/.
Safety
There are no known safety issues with this lesson.
Preconceptions/Misconceptions
CLM003: The maximum height the Sun reaches in the sky on any given day is the same everywhere on
earth (AAAS Project 2061, n.d.).
Circadian rhythms are found in single-celled organisms, plants, and animals (including humans) (Dunlap
et al., 2004).
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Procedures/Instructional Strategy
ENGAGE
1. Review the following northern hemisphere dates with students:
a. Summer Solstice (first day of summer): June 21, 2015
b. Fall Equinox (first day of fall) September: 23, 2015
c. Winter Solstice (first day of winter): December 21, 2015
d. Spring Equinox (first day of spring): March 20, 2015
2. Have students work in groups of three to four. Provide each group a large white board or large
piece of paper (18” x 24”). Have students divide the white board or paper into 4 quadrants as
shown below. In the first quadrant write the word “summer.” In the second quadrant write the
word “fall.” In the third quadrant write the word “winter.” And in the fourth quadrant write the
word “spring.”
Summer
Fall
Winter
Spring
3. Ask students to list natural events that signal a change in seasons. Encourage students to list
events that are specific to their geographic region.
Hint: By providing each student with a different colored marker, the teacher will be able to easily
visualize who is contributing.
Example answers could include changes in day length, changes in weather (precipitation and
temperature), bloom times, planting/harvesting times, hibernation, migration, etc.
4. Circulate the room as students work. Assist any groups with brainstorming as needed.
Differentiation strategy: This activity could be done as a whole group. For English language
learners, consider asking them to draw pictures of events that represent the seasons.
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5. After 10 minutes, have each group write a claim that identifies which of the factors listed on
their board or paper would cause birds to migrate or bears to hibernate (or other behavioral
responses they listed). Students should also justify why this factor is important.
Example answers: Day length is important because it tells birds when to migrate. Temperature
signals hibernation.
6. Call on each group of students, asking them to explain their claim and the justification for their
claim. The following questions can help the students develop their claim:
a. What observations or inferences can you use to support your claim?
b. What scientific reason or scientific principle can you use to support your justification?
c. How does your claim demonstrate an organism’s ability to adapt to its environment?
d. How do organisms respond to changes in seasons?
e. How do organisms benefit from changes in seasons?
7. Hold a class discussion regarding the student claims. Ask the class the following questions:
a. How many claims identified a nonliving factor as the most important factor? Answers
will vary.
b. How many identified a living factor as the most important? Answers will vary.
c. How do nonliving factors impact living things? Answers will vary.
d. In what ways are humans affected by seasonal change? Answers will vary.
Note: Teachers may wish to introduce the terms abiotic factor and biotic factor at this time.
Abiotic factors are the nonliving components of the environment, such as temperature, sunlight,
and humidity. Biotic factors are the living components of the environment and include organisms
such as producers, consumers, and decomposers.
8. Tell students that they have identified year-long cycles and changes. These are called circannual
rhythms (e.g., migration, hibernation, etc). A seasonal change that is not a behavior is day
length, or the amount of daylight an area receives. Ask students to give examples of how the
amount of daylight an area receives affects plants and animals. Note: To prompt discussion, it
may be useful to give examples of local, seasonal plant growth and/or animal behaviors with
which students are familiar.
Possible Answers: Animal behaviors such as migration and hibernation; plant behaviors such as
flowering and losing leaves.
9. Tell students that environmental triggers may vary, but they are going to focus on one they
know exists: day length. Lead students to the realization that the amount of day length is critical
for plants and animals. Ask students to define day length.
Day length refers to the length of time there is light in the sky on a daily basis.
Note: Other factors that are important include precipitation and temperature.
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EXPLORE
1. Pass out Student Sheet #1. This activity will bridge two days. Pace your students so that they
spend time on each step and can supply thoughtful answers supported by evidence from the
Journey North website (see Student Sheet #1).
EXPLAIN
1. Tell students that the Journey North website shows cycles over the course of a year. Are there
any cycles humans have? Prompt students to think about if there is anything in the environment
that triggers feeling tired, hungry, energetic, sleepy, etc.
Note: Answers can be based on a daily (circadian) and/or seasonal (circannual) basis.
Answers will vary.
2. Inform students that although people don’t respond to environmental cues exactly like plants
and animals, they still have cycles that are driven by external factors such as daylight. Ask
students for examples of 24-hour animal behavior and evidence of this behavior.
Possible answers include nocturnal animals hunting at night, diurnal birds not singing at night,
morning glory flowers blooming when the sun rises but closing up when the sun sets, etc.
3. Explain circadian rhythms in humans using the following possible sources:
a. Fact Sheet
http://www.nigms.nih.gov/education/pages/factsheet_circadianrhythms.aspx
b. Cyclic Behavior of Animals http://www.ck12.org/biology/Cyclic-Behavior-ofAnimals/lesson/Cyclic-Behavior-of-Animals/
Note: This resource is a creative commons resource and can be printed and distributed to
students.
ELABORATE
1. Show students Figure 1 (below), the human biological circadian clock. Explain that melatonin is a
chemical produced by the pineal gland in the brain. The body produces more when there is less
light, which makes humans less alert and more sleepy. Exposure to light decreases the amount
of melatonin produced (For information on melatonin, visit http://sleepfoundation.org/sleeptopics/melatonin-and-sleep.)
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Figure 1. The human biological circadian clock. These times and designations can vary for a given individual on
different days and, of course, among individuals.
2. Have students work with a partner to answer the following questions:
a. What relationships exist between a person’s body functions and the light/dark cycle (24
hours)?
Answers will vary, but students should cite evidence from the image. This can include
when melatonin secretion decreases in the morning as the Sun rises, the body starts
normal processes again and will grow more alert. When melatonin secretion increases
at night after the Sun has set, the body suppresses normal functioning so the person can
fall asleep.
b. How does your body get you ready for sleep?
Answer: Melatonin rise is associated with onset of sleep.
c. How does your body get you ready for waking up?
Answer: The body produces less melatonin with an increase in light, which signals the
body to wake up.
d. When is the optimal time that students should take tests?
Answer: According to the image, 10:00 a.m. is a time of “high alertness.” This may be an
optimal time to take a test.
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e. When is the optimal time to play sports?
Answer: From 14:30 (2:30 p.m.) to 17:00 (5:00 p.m.) are times of best coordination,
fastest reaction time, and greatest cardiovascular efficiency and muscular strength.
Therefore, the best time to play sports would be between 2:30 and 5:00 p.m.
3. Discuss the answers with the class. You may wish to have students hypothesize about the
following:
a. Why do you think humans follow a 24-hour circadian cycle?
Scientists believe that living organisms adapted the 24-hour circadian cycle to help
adapt to the Earth’s 24-hour rotation (see
http://learn.genetics.utah.edu/content/inheritance/clockgenes/).
b. You fly in an airplane to Paris, leaving Washington, DC at 4:30 p.m. and arriving in Paris
the next day at 8:45 a.m. What effect do you think this will have on your body? Note:
Paris is six hours ahead of Washington, DC.
Answer: You will probably suffer something called jet lag in which your regular sleep
patterns are out of sync with the actual time. That means that your body thinks it is a
different time than the actual time. When your plane lands in Paris, your body will think
it is 2:45 a.m. instead of 8:45 a.m.
EVALUATE
Based on the Journey North maps, students should have an understanding that different organisms have
different circadian rhythms, but that the circadian rhythm is affected by light/day length.
Have students create a concept map or T-chart showing the link between organisms and both circadian
(daily) and circannual (seasonal) rhythms.
Example concept map
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Example T-chart comparing daily and seasonal rhythms
Examples of Daily Rhythms
Waking up, sleeping, blood pressure, body
temperature
Examples of Seasonal Rhythms
Migration, bloom times, leafing out, hibernation,
reproduction, flowering
Have students write a response to the following question: How does light affect circadian rhythms?
Look for student understanding of the manifestations of circadian rhythms in different organisms
(concept map). Some students may answer the question with “Flowers bloom earlier.” This answer is
not complete. While it shows that the student understands flowering is a result of circadian rhythms, it
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does not use evidence for justification. An acceptable response would be: “Flowers bloom earlier when
day length is longer because there is more light.” This answer shows the student is making the
connection between light and circadian rhythms. Expect students to give the evidence (and reasoning) in
their responses.
Differentiated Instruction
Provide students who have difficulty navigating the Journey North site with printed maps downloaded
from the site.
Allow students to work in groups.
Emphasizing the connections to various countries can help engage students with different cultural
backgrounds.
Extension
1. Natural light is important to more than just behavior. Show students the following images and have
them investigate the relationship between natural light and Vitamin D.
Answer: Natural light, or sunlight, is necessary to convert a chemical in the skin into Vitamin D3, which is
transported to the liver and kidneys where it is made into Vitamin D. Sunlight is more than just visible
light, it also includes infrared and ultraviolet (UV). UV light is the focus of this problem.
Rickets is a disorder caused by a deficiency of Vitamin D. It can result in stunted growth. Therefore, light
affects growth as well as behavior.
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Figure 2. Rickets leg x-ray. Image courtesy: Dr. Michael L. Richardson, Licensed under CC BY-SA 1.0.
Figure 3. Rickets x-ray. Image courtesy: Frank Gaillard, Licensed under CC BY-SA 3.0.
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Figure 4. Illustration of legs with normal bone growth versus rickets.
References
Dunlap,J., Loros, J., DeCoursey, P. (2004). Chronobiology: Biological Timekeeping. Sinauer Associates.
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Name: ________________________________
Date: _____________
Student Sheet #1: Exploring Seasonal
Circadian Rhythms
Objective
Determine the nature of circadian rhythms within organisms.
Procedure
Go to the Journey North website at http://www.learner.org/jnorth/maps/photo_spring2015.html to
access the 2015 Sunlight and Seasons Information Map, which shows the reported amount of day length
across the United States.
Part 1: Examining Photoperiod
Select November 1 from the dropdown calendar (see circled location in Figure 1). What pattern do you
see? Note: Photoperiod refers to the amount of sunlight an area receives.
Now select May 1 from the dropdown calendar. What pattern do you see?
Figure 1. 2015 Sunlight and seasons information map.
Part 2: Exploring Spring 2015 Data
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Go to http://www.learner.org/jnorth/maps/galleries/2015/spring.html (see Figure 2). You will be
exploring data collected during the spring of 2015.
Select one of the following species to investigate: robins, earthworms, common loons, singing frogs, or
barn swallow. Note: Selecting the word home that appears underneath each map will lead to more
information about the featured species.
Select the map for your selected species. What do the dates of the sightings tell you about your chosen
species?
Figure 2. Spring 2015 Journey North data.
Part 3: Exploring Archived Data Sets
Go to https://www.learner.org/jnorth/maps/archives.html (see Figure 3) to explore additional data sets
and interactive maps.
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a. Under the box that says “Spring 2014 Sightings,” select the link to “Spring 2014 Maps.” You will
go to a page that features 22 maps, some static and others interactive. The maps represent
observable events related to plants, animals, and weather. Each of the selections contains a
map, a list of reported sightings, and a background page about the species.
Select an organism whose behavior you would like to explore further. Note: Do NOT select
symbolic monarchs, whooping cranes, signs of the seasons, or habitat projects. Select the map
for your organism. For some species, such as the Monarch butterfly, you can filter the results by
selecting various dates.
b. Examine three years of sightings for your species. Describe any similarities and/or differences
between the maps. Things to consider:

Is the activity level of your species (e.g., migration) similar each year? If yes, what
factors would trigger an organism to react in the same way each year?

Is there a specific week or month of maximum sightings?
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Figure 3. Past seasons data from Journey North.
Part 4: Investigating an Organism’s Relationship to Day Length
Using either the current season or past seasons, develop a question to explore related to an organism’s
activity and day length. For example, Is there a relationship between day length and the first frog heard
singing?
Figure 4 shows that as day length increases, more frogs could be heard singing. In addition, frogs in
more northern regions begin singing later in the spring. This is due to colder temperatures.
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.
Figure 3. Map showing data collected of frogs first heard singing.
Using a species of your choice, develop a question to investigate to determine how day length impacts
an organism. Use the maps from the Journey North website to answer your question.
a. Your question:
b. What patterns do you notice?
c. What do you think is happening and why?
d. What is your hypothesis?
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e. What did you find out when you investigated your question?
f.
What other explanations could be plausible (i.e., an alternative hypothesis)?
Part 5: Going Further
What other types of behaviors do you think are linked to day length or the amount of light organisms
receive? Use the Journey North site to support your ideas. Below are some questions to consider:
a. When did your chosen species begin to migrate? Note: Not all species migrate.
b. Was there a peak week during which your selected species was spotted?
c. Is the activity of your species linked to the availability of food and/or habitat? For example, what
is the relationship between: Monarch butterflies and milkweed? Between robins and
earthworms? Between leaf out and orioles?
Extend
The study of seasonal changes shown by plants and animals is called phenology. As the climate gets
warmer, species are moving farther north. Many plants are now blooming earlier than they used to in
the past. What effect will this have on species of birds that depend on plants for seeds and fruit?
Optional Project: Keep a journal in which you document temperature, length of day, and sightings of a
specific organism.
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Name: _____________KEY___________________
Date: _____________
Student Sheet #1: Exploring Seasonal
Circadian Rhythms
Objective
Determine the nature of circadian rhythms within organisms.
Procedure
Go to the Journey North website at http://www.learner.org/jnorth/maps/photo_spring2015.html to
access the 2015 Sunlight and Seasons Information Map, which shows the reported amount of day length
across the United States.
Part 1: Examining Photoperiod
Select November 1 from the dropdown calendar (see circled location in Figure 1). What pattern do you
see? Note: Photoperiod refers to the amount of sunlight an area receives.
The photoperiod or day length decreases with increasing latitude.
Now select May 1 from the dropdown calendar. What pattern do you see?
The photoperiod or day length increases with increasing latitude.
Figure 4. 2015 Sunlight and seasons information map.
Part 2: Exploring Spring 2015 Data
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Go to http://www.learner.org/jnorth/maps/galleries/2015/spring.html (see Figure 2). You will be
exploring data collected during the spring of 2015.
Select one of the following species to investigate: robins, earthworms, common loons, singing frogs, or
barn swallow. Note: Selecting the word home that appears underneath each map will lead to more
information about the featured species.
Select the map for your selected species. What do the dates of the sightings tell you about your chosen
species? Answer: the season progresses the organism is spotted in more northerly locations.
Figure 5. Spring 2015 Journey North data.
Part 3: Exploring Archived Data Sets
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Go to https://www.learner.org/jnorth/maps/archives.html (see Figure 3) to explore additional data sets
and interactive maps.
c. Under the box that says “Spring 2014 Sightings,” select the link to “Spring 2014 Maps.” You will
go to a page that features 22 maps, some static and others interactive. The maps represent
observable events related to plants, animals, and weather. Each of the selections contains a
map, a list of reported sightings, and a background page about the species.
Select an organism whose behavior you would like to explore further. Note: Do NOT select
symbolic monarchs, whooping cranes, signs of the seasons, or habitat projects. Select the map
for your organism. For some species, such as the Monarch butterfly, you can filter the results by
selecting various dates.
d. Examine three years of sightings for your species. Describe any similarities and/or differences
between the maps. Things to consider:


Is the activity level of your species (e.g., migration) similar each year? If yes, what
factors would trigger an organism to react in the same way each year?
Is there a specific week or month of maximum sightings?
21
Figure 3. Past seasons data from Journey North.
Part 4: Investigating an Organism’s Relationship to Day Length
Using either the current season or past seasons, develop a question to explore related to an organism’s
activity and day length. For example, Is there a relationship between day length and the first frog heard
singing?
Figure 4 shows that as day length increases, more frogs could be heard singing. In addition, frogs in
more northern regions begin singing later in the spring. This is due to colder temperatures.
22
.
Figure 6. Map showing data collected of frogs first heard singing.
Using a species of your choice, develop a question to investigate to determine how day length impacts
an organism. Use the maps from the Journey North website to answer your question.
g. Your question:
h. What patterns do you notice?
i.
What do you think is happening and why?
j.
What is your hypothesis?
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k. What did you find out when you investigated your question?
l.
What other explanations could be plausible (i.e., an alternative hypothesis)?
Part 5: Going Further
What other types of behaviors do you think are linked to day length or the amount of light organisms
receive? Use the Journey North site to support your ideas. Below are some questions to consider:
d. When did your chosen species begin to migrate? Note: Not all species migrate.
e. Was there a peak week during which your selected species was spotted?
f.
Is the activity of your species linked to the availability of food and/or habitat? For example, what
is the relationship between: Monarch butterflies and milkweed? Between robins and
earthworms? Between leaf out and orioles?
Possible answers include migration and bloom times. Journey North has data related to migration of
insects, gray whales, and bird species. Data related to milkweed blooming times and leaf-out of
deciduous trees can also be examined.
Extend
The study of seasonal changes shown by plants and animals is called phenology. As the climate gets
warmer, species are moving farther north. Many plants are now blooming earlier than they used to in
the past. What effect will this have on species of birds that depend on plants for seeds and fruit?
The birds are out of sync with their food supply. This may impact their ability to successfully raise their
young.
Optional Project: Keep a journal in which you document temperature, length of day, and sightings of a
specific organism.
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Optional Maps
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