National Agricultural Literacy Curriculum Matrix
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9 - 12
Students will understand how photoperiodism impacts plants and animals in the environment and learn how egg farms use this science to manage the production of eggs by their hens.
- Scenario image to display for class
- Blank sheet of paper or interactive science notebook, 1 per student
- Photoperiodism Notebook Cutouts, 1 copy per student
- Scissors and tape or glue
Essential Files (maps, charts, pictures, or documents)
protein: an essential nutrient responsible for building tissue, cells and muscle
clutch: the name of a group of eggs produced by birds, amphibians or reptiles in a series of days
photoperiodism: the physiological reaction of organisms to the length of day or night
Did you know? (Ag Facts)
- In 2017 the average American ate 274 eggs per year.1
- Eggs provide the least expensive source of high-quality protein for our diets. Eggs are followed by milk and chicken.2
- Hens can lay up to 1 egg per day. It takes approximately 25-26 hours for a hen to produce an egg.3
Background Agricultural Connections
Interest Approach – Engagement
- Define the word phenomenon as, a fact or situation that is observed to exist or happen.
- Introduce students to the following phenomena by displaying the following image:
- Discuss scenario one. Ask, "Could there be a scientific explanation for why the hens slowed their production of eggs?"
- Discuss scenario two. Ask, "Is it possible that there is a scientific explanation for this economic phenomenon?"
- Leave the questions open-ended and instruct students that they will be seeking to find the answer in the lesson.
Activity 1: The Science of Egg Laying
- Display the Animals Who Lay Eggs image for your class to see. Ask students, "What do all of these animals have in common?" Allow students to think and offer answers until they identify that the female of each of these species lays eggs. Clarify that with some exceptions most birds, reptiles, and amphibians lay eggs. Each egg varies in size, shape, and consistency (soft or hard shells).
- Ask students to raise their hand if they had an egg for breakfast or any food with eggs as an ingredient in the last 24 hours. All or most students should likely raise their hand. Ask, "What species of animal lays the eggs we typically eat?" (chicken)
- Ask students why we don't typically eat eggs from ducks, turkeys, or other species like snakes or lizards. As students offer answers, provide guiding questions to lead them to think about raising each animal on a farm. Point out that our food is produced on farms, not hunted and gathered. Therefore, our food comes from plants and animals that produce desirable products efficiently. In the case of eggs, efficiency can be measured by considering the size and quantity of eggs the animal can produce compared to the cost of breeding, feeding, and housing the animal. It may be helpful to provide the following statistics for illustration:
- Turkey hens can lay around 100 eggs per year.
- Female geese can lay around 40 eggs per year.
- Female ducks can lay between 60 and 150 eggs per year depending on the breed.
- Chicken hens can lay up to 300 eggs per year.
- Note that each of these numbers represent birds raised on farms where the eggs are collected each day. In the wild the bird would only lay enough eggs to complete a nest, often called a clutch. After the clutch was complete the bird would stop laying eggs and set on them until they hatch. On a farm, collecting the eggs each day causes the bird to continue to lay eggs longer than if it was in the wild.
- Open the Egg Farms Prezi and review it as a class. At the end of the Prezi, list the following observed phenomena students have been introduced to so far.
- Chickens lay more eggs in the spring and summer than they do in the fall and winter.
- Chickens do not lay eggs late in the day or during the night. Rather, they will skip a day of egg production and lay the next morning.
- The price of free-range chicken eggs can increase in the winter. The cost of conventionally produced eggs usually does not.
Activity 2: Explaining Photoperiodism
- Give each student 1 sheet of blank paper or have them open to a new page in their interactive science notebook.
- Instruct students to title the page with the word "Photoperiodism" and record the definition (the physiological reaction of organisms to the length of day or night). Clarify that photoperiodism takes place in both plants and animals.
- Have students draw a diagonal line from the top right corner of their page to the bottom left corner. Draw and color a sun on one side of the line and a moon on the opposite side to signify day and night. (display image for illustration)
- Ask students, "How can sunlight impact plants and animals?" Follow up with the question, "Can darkness also impact plants and animals?" Allow students to draw from their own background knowledge and observations to offer answers.
- Next, ask students to think about the length of day (amount of light vs darkness) in the spring and summer compared to the length of day in the fall and winter. Is there a difference? (Yes, daylight is long in the spring and summer and short in the fall and winter due to the rotation of the earth around the sun) Have students record in their notebooks that spring and summer have long days and short nights while fall and winter have short days and long nights
- Give each student 1 copy of the Photoperiodism Notebook Cutouts. Instruct students to cut out each diagram and place it on their note paper or in their science notebook.
- Assign as homework or allow students time to research examples of photoperiodism in nature. Students should find five examples of plants or animals reacting to long days and five examples of plants or animals reacting to short days. Write the name of the plant or animal on the outside of each tab and describe the photoperiodic reaction on the inside of the tab. Many examples exist in nature. A few examples your students may find include:
- Female sheep and goats only have an estrus (breeding) cycle when the days are short.
- Female horses only have an estrus (breeding) cycle when the days are long.
- Poinsettia plants flower and their leaves turn red when the days are short.
- Chrysanthemum plants flower in the fall when the days are short.
- Pea, lettuce, and wheat plants will only flower when the days are long.
- After the notes page is complete, draw your students' attention to the list of phenomena you listed on the board at the end of Activity 1. Could egg production in hens be influenced by sunlight? (Yes. Hens will naturally slow their egg production as the days get shorter in the fall and may even stop producing eggs in the shortest days of winter.) Explain to students that egg farmers have various types of housing for hens that are specially engineered with automatic lighting. When the days begin getting shorter, the lights turn on at dusk to mimic a long summer day. This results in hens sustaining their egg production through the winter providing a year-round supply of eggs. See the Enriching Activity below for an explanation of why free-range eggs may be more expensive in the winter while conventional eggs are typically not.
Concept Elaboration and Evaluation
After completing these activities, review and summarize the following key concepts:
- Photoperiodism is the physiological reaction of organisms to the length of day or night.
- Many plants and animals in our environment, including domestic hens that lay eggs, are impacted by either the presence or absence of sunlight.
- Understanding science, such as the principle of photoperiodism, allows farmers to increase the productivity of their farms to make them more efficient.
We welcome your feedback! Please take a minute to tell us how to make this lesson better or to give us a few gold stars!
To help students better understand various styles of hen housing, give students a video tour of Burnbrae Farms, a large egg farm in Canada which uses several styles of hen-housing. Have students watch each video and compare and contrast the benefits and disadvantages for each housing system in a T-chart. After completing the activity, students should recognize that when accounting for all factors there is no single "best" or "worst" system. Each producer and consumer chooses their preference of egg production systems. As a class, discuss how free-range housing may prove more difficult to provide supplemental lighting in the winter than other styles of housing. While supplemental lighting can be provided in nest houses of free-range egg farms, the hens have more access to the outdoors leading to more likelihood of the hens decreasing their winter egg production. Following simple economic rules of supply and demand free range egg prices may rise in the winter while conventional and cage-free eggs do not.
Suggested Companion Resources
Agricultural Literacy Outcomes
Culture, Society, Economy & Geography
- Discuss how agricultural practices have increased agricultural productivity and have impacted (pro and con) the development of the global economy, population, and sustainability (T5.9-12.e)
Education Content Standards
Animal Systems Career Pathway
AS.01.02Assess and select animal production methods for use in animal systems based upon their effectiveness and impacts.
AS.02.01Demonstrate management techniques that ensure animal welfare.
HS-ETS1: Engineering Design
HS-ETS1-2Design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems that can be solved through engineering.
HS-LS1 From Molecules to Organisms: Structures and Processes
HS-LS1-3Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.
Common Core Connections
Reading: Anchor Standards
CCSS.ELA-LITERACY.CCRA.R.7Integrate and evaluate content presented in diverse media and formats, including visually and quantitatively, as well as in words.
Speaking and Listening: Anchor Standards
CCSS.ELA-LITERACY.CCRA.SL.1Prepare for and participate effectively in a range of conversations and collaborations with diverse partners, building on others’ ideas and expressing their own clearly and persuasively.
CCSS.ELA-LITERACY.CCRA.SL.2Integrate and evaluate information presented in diverse media and formats, including visually, quantitatively, and orally.