Science+Wiki+Uses

**__FROM EGG TO CHICKEN__** Here are a few different definitions that could be assumed and their logical outcomes.[|[6]] when we are trying to determine what comes first- the egg or the chicken:
 * **If the egg is not necessarily of any specific type:** Then it could be said that the egg came first, because other animals had been laying eggs long before chickens existed, such as the [|dinosaurs]. In biology, [|egg is used as a general term] in this way.
 * **If only an egg that will //hatch// into a chicken can be considered a chicken egg:** Then a re-consideration of the original question suggests: Some animal other than a chicken laid the first chicken egg which contained the first chicken. In this case the chicken egg came before the chicken. In reality, many scientific theories suggest that this would not have been a simple event. For example, the theory of [|Punctuated equilibrium] theorizes that the actual [|speciation] of an organism from its ancestral species is usually the result of many mutations combined with new geographical surroundings, called [|Cladogenesis].
 * **If only an egg laid //by// a chicken can be considered a chicken egg:** Then a re-consideration of the original question suggests: The first chicken (which hatched from a non-chicken egg) laid the first chicken egg. In this case the chicken came before the chicken egg. Again, this would not necessarily be a straightforward event.
 * **If only an egg that is laid by a chicken //and// that will hatch into a chicken can be considered a chicken egg:** Then the first chicken came from a different type of egg (not a chicken egg) and laid the first chicken egg. In this case eggs (in general) came first, the chicken came after, and the chicken egg came last.

Chicken Lifecycle Lesson Plan

TITLE: The Life Cycle of a Chicken leg AUTHOR: Cerrie Montgomery GRADE LEVEL/SUBJECT: Science/Grade 2 CURRICULUM STANDARD: LS-E-B2 Observe and describe life cycles of plants and animals in a classroom. OVERVIEW: All animals have a life cycle that describes the different stages their life takes. Some lives are happy and some are quite tragic. We have chosen to study the life cycle of a chicken. A chicken has a sad, sad life. PURPOSE: This activity gives students the opportunity to directly observe the stages in the life cycle of a chicken. OBJECTIVES: Students will be able to: 1. Observe life cycle of a chicken. 2. Draw pictures and describe the life cycle of a chicken. RESOURCES/MATERIALS: Incubator Chicken Eggs Paper and crayons E-mail address Internet addresses: http://ofcn.org/cyber.serv/academy/ace/sci/cecsci/cecsci015.html http://situweb.stockportmbc.gov.uk/pages/links/schools/primary/alexpkin/chicks/chick4.htm http://206.76.26.9/Highschool/TechPrep/TLOAC.htm http://www.siec.k12.in.us/~west/strange/emu.htm E-mail addresses: Tpayton@dmrtc.net ACTIVITIES AND PROCEDURES: 1. Set up incubator with fertilized chicken eggs. 2. Incubate fertilized chicken eggs for a period of 20 days. 3. Periodically hold the eggs to student's ears. Days before hatching the students hear the chicks peeping inside. 4. The teacher will discuss the developing embryo in various stages of growth. 5. Once chicks are born, born place the chicks in a box with food and water. Place a light near the chick. 6. Have students draw pictures and describe the life cycle of a chicken. TYING IT ALL TOGETHER: Students may post their pictures on the bulletin board and describe the life cycle of chicken to the class. Students may E-mail other classes that are studying similar life cycles to share their experiences. EVALUATION: Student participation in drawing of pictures and describing the life cycle of a chicken.

http://www.bravebirds.org/chickfree.pdf

Chicken sounds http://www.ilovewavs.com/Effects/Animals/Animals.htm || The Formation of an Egg :
 * Reproduction**:
 * **Cross Section of a Newly Laid Egg**

This entire trip through the oviduct takes about one day.
 * The Yolk:** The chicken egg starts as an egg yolk inside a hen. A yolk (called an oocyte at this point) is produced by the hen's ovary in a process called ovulation.
 * Fertilization:** The yolk is released into the oviduct (a long, spiraling tube in the hen's reproductive system), where it can be fertilized internally (inside the hen) by a sperm.
 * The Egg White (albumin)**: The yolk continues down the oviduct (whether or not it is fertilized) and is covered with a membrane (called the vitelline membrane), structural fibers, and layers of albumin (the egg white). This part of the oviduct is called the magnus.
 * The Chalazae**: As the egg goes down through the oviduct, it is continually rotating within the spiraling tube. This movement twists the structural fibers (called the chalazae), which form rope-like strands that anchor the yolk in the thick egg white. There are two chalazae anchoring each yolk, on opposite ends of the egg.
 * The Eggshell**: The eggshell is deposited around the egg in the lower part of the oviduct of the hen, just before it is laid. The shell is made of calcite, a crystalline form of calcium carbonate.
 * Growth of the Embryo:** The fertilized blastodisc (now called the blastoderm) grows and becomes the embryo. As the embryo grows, its primary food source is the yolk. Waste products (like urea) collect in a sack called the allantois. The exchange of oxygen and carbon dioxide gas occurs through the eggshell; the chorion lines the inside surface of the egg and is connected to the blood vessels of the embryo.
 * The Incubation Period:** The embryo develops inside the egg for 21 days (the incubation period), until a chick pecks its way out of its eggshell and is hatched.

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