Target Grade Level / Age Range:
One 40 minute period
During the sexual reproduction unit, students learn about the egg as being the female gamete, and the sperm as being the male gamete. Each having half the number of chromosomes needed for an embryo. Today, students will learn about chicken eggs. A happy hen is one who has long days, nutritious food, clean water, and a perch away from predators. Six billion eggs are consumed in the United States each year! Students will learn how to care for hens and know what each part of the egg is for.
Essential Files (maps, charts, pictures, or documents)
- PowerPoint presentation
- 2 Truths & a Lie Game
- Egg part matching worksheet https://web.extension.illinois.edu/eggs/pdfs/worksheets.pdf (page 2)
Vocabulary (with definitions)
- Shell: a thin, hard outer layer of an egg; made of CaCO 3 (calcium carbonate); has 7,000 pores to allow gas exchange!
- Inner/outer membranes: transparent protein made of keratin, thin membranes that keep bacteria out.
- Air cell: between the inner and outer membranes is an air cell, which is caused from when the egg cools, it contracts. The older the egg, the larger the air cell.
- Albumen: The egg white that contains 40 different proteins.
- Chalazae: 2 chords on each end to hold the yolk in place. These are made of mucin fibers; seen more prominently in fresher eggs.
- Yolk: food source for growing chick, if the egg was fertilized. Has fats needed for fetus.
- Germinal disc: where DNA is found; this is where rooster’s sperm would enter for fertilization.
- White yolk: at the center of the larger yolk; has less fat. Also called the latebra.
- Fertilized egg: when sperm has penetrated the egg; chick embryo will start developing.
- Vitelline membrane: clear membrane surrounding yolk.
- Layers: chickens that lay eggs
Background – Agricultural Connections (what would a teacher need to know to be able to teach this content)
Around the age of 6 months, a hen can start laying eggs. She can lay one per day; it takes 26 hours to fully form. Her duration of laying will be 3-4 years. Production and shell quality decrease as the years go by, whereas, the egg size will increase.
Layers need at least 14 hours of day light; lights plugged into a timer can help to add hours. A 60 Watt bulb hung 7 feet up is sufficient for a small/medium brood.
Hens must have a diet high in Calcium so that the egg shells will be hard enough.
Besides an abundance of light and nutritious diet, hens must have adequate space. In the coop, each bird needs 1.5 ft 2. They are natural ‘perchers.’ They prefer to sleep on a perch, which also helps with predators being less of a risk.
There are 3 main ways to identify which hens are laying : the color of the comb/wattle, pigmentation in face and feet, as well as abdominal fat. In layers, they will exhibit bright red combs/wattles. The yellow pigment in their face and feet will start fading and be lighter in color than others. Additionally, their abdominal fat will be much less in layers.
Hens may stop laying if there is not enough food or fresh water available, not enough daylight, or the hen may be sick. This means it’s crucial to provide the hen with both the proper environment and feed.
Interest Approach – Engagement (what will you do to engage students at the beginning of the lesson)
Ask the class: When was the last time you ate an egg? (if some say they don’t like eggs, ask them if they’ve eaten a cupcake or cookie or anything else that has eggs in them!) SIX BILLION eggs are eaten in the U.S. every year! Today, we are going to learn about what it takes to produce eggs, and we will learn all about the various parts inside the egg.
Ask the class: How many different ways we can eat eggs? How many different foods are eggs in? Take a poll – how many people like eggs? Scrambled, Fried, Boiled, (make a bar graph of results)
- Share slides 1-12 of the PowerPoint. Complete the first and second quick quizzes.
- Pass out a copy of the egg part Matching worksheet to each student. Ask students to first try filling it out on their own. Allow 5 minutes or work time. Then go over the worksheet and ensure all students have the correct answers.
- Continue presenting slides 13-16 of the PowerPoint.
- Crack open an egg for the large group to pass around or if more eggs available, one per group of three. Students can use the toothpicks to gently examine the different parts of the egg.
- Continue presenting slides 17-19 of the PowerPoint.
- In the groups of three, pass out one of the two truths and a lie questions to each student. Have the students take turns reading their truths and lies and having thier partners guess which one is the lie. When they have completed the questions and the guesses, challenge them to write their own truths and lies about chickens and egg production based on information they learned in the lesson. Allow for 5-10 minutes of work time. Once students have come up with their own material, they can again challenge their partners. See how many rounds each pair can ‘play’ using different facts each time. Collect the papers from each group and give them to a different group to keep the game play going.
- When the game has been exhausted, display the final slide for the students as their exit ticket. Ask each student to write their response on a piece of paper and show the teacher before they leave for the day.
Did you know? (Ag facts)
- If a hen mates before the egg forms, the embryo will not develop once the egg is refrigerated.
- Hens can lay fertilized eggs for a week, even if she mated just once!
- You can tell if an egg is fertilized by ‘candling.’ If it looks opaque, it’s fertilized. Blood spots in the embryo also indicate that the egg is fertilized.
- Most scientists agree that the yolk is the largest cell. Specifically, an ostrich yolk is the largest cell. (the ostrich egg weighs 3.3 lbs) *show picture of ostrich egg next to chicken egg*
- Share story of my encounter with an ostrich in Florida when I was in 4 th grade.
- When the egg is laid, it initially is 106 degrees Fahrenheit. As it cools, it contracts and the air cell forms inside the inner/outer membranes.
Extension Activities (how students can carry this beyond the classroom)
- Students can try the at home experiment of putting an egg in a cup of vinegar for 2 days. Vinegar (acetic acid) will leach all the calcium out of the shell; it will feel like a leather egg!
- The next time the student is helping to cook and an egg is involved, the student should teach the parent all the parts on the inside of the egg!
- From the matching worksheet, flash cards can be made. Can play a matching game anytime, anywhere!
- Prepare eggs in different forms and allow students to taste them. (scrambled, fried, boiled)
Suggested Companion Resources (books and websites)
- Chicks and Chickens by Gail Gibbons
Clinton Middle School
Agriculture Literacy Outcomes
- T4.6-8.f—Explain the harmful and beneficial impacts of various organisms related to agricultural production and processing (e.g. harmful bacteria/beneficial bacteria, harmful/beneficial insects) and the technology developed to influence these organisms.
- T2.6-8.e—Identify strategies for housing for animal welfare and the safety of animal products (e.g. meat, milk, eggs)
Iowa Core Standards
- HS-LS3-1. Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.
- MS-LS4-5. Gather & synthesize information about the technologies that have changed the way humans influence the inheritance of desired traits in organisms.
- MS-LS3-2. Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.
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