Classroom time: 30 to 45 minutes

Students will be able to:

1. recognize the characteristics of eggs which determine their grade and size.

2. develop creative problem-solving skills by analyzing data in a logic puzzle.

1. consumer education: identifying, comparing and analyzing

2. math: creative problem solving and logical reasoning

3. critical thinking: evaluating clues to logic puzzle

1. Eggs Make the Grade! (activity sheet 7)

2. Shell eggs of various grades and sizes, both raw and hardcooked, optional

Eggs are a simple, self-contained food made up of several parts:

• the shell;

• the albumen, or white, which includes the chalazae, those thick, twisted strands of white which center the yolk in the white;

• the yolk, or yellow part;

• the air cell, an air-filled pocket at the large end of the egg.

     All states have laws regulating the sales of eggs and they all require the use of the U.S. Standards, Grades and Weight Classes for Shell Eggs. Grade is determined by examining the interior and exterior quality of the egg at the time it is packed and is designated by the letters AA, A and B, with AA being the highest.

     The shell is inspected for cleanliness, soundness, texture and shape. Shell color is not a factor in judging quality. The exterior standards require all eggs to be clean, but a little staining is permitted in grade B. All eggs must have sound, unbroken shells. Shells of grade AA and A eggs are ovals with one end larger than the other. Abnormally shaped eggs or those with very bumpy textures or ridges, thin spots or rough areas are graded as B.

     Using a candler, an intense light beam, the albumen is inspected for firmness or thickness and clarity (no discolorations or foreign bodies), the yolk for its size, shape and lack of blemishes. The air cell is judged on its size. You can easily see the interior standards for the albumen and yolk in an egg broken out of its shell and see where an air cell was present by inspecting the flattened end of a peeled, hard-cooked egg.

     When broken out, the contents of a grade AA egg cover a small area. The white is firm. There is much thick white surrounding the yolk and a small amount of thin white. The yolk is round and upstanding. The air cell is about the size of a dime and doesn’t exceed 1/8 inch in depth.

     When broken out, the contents of a grade A egg cover a moderate area. The white is reasonably firm. There is a considerable amount of thick white and a medium amount of thin white. The yolk is round and upstanding. The air cell is less than 3/16 inch deep. There is very little difference in quality between grade AA and grade A eggs.

     When broken out, the contents of a grade B egg cover a very wide area. The white is weak and watery. There is no thick white and the large amount of thin white is thinly spread. The yolk is enlarged and flattened. The air cell may be over 3/16 inch deep. Grade B eggs are just as wholesome to eat, but rate lower in appearance. Almost no grade B eggs are sold at retail. Some are used by institutional egg users such as bakeries, but most are processed into egg products.

     There is no difference in nutritional value among the three grades. Storage is very important, though. Eggs lose quality very rapidly at room temperature. A grade AA egg can quickly become a grade A or even a grade B if it isn’t properly refrigerated.

     Size and grade are two entirely different factors and have no relationship to one another. Size is determined by the minimum net weight per dozen. The six egg sizes established by the the U.S. Department of Agriculture are Jumbo (30 oz.), Extra Large (27 oz.), Large (24 oz.), Medium (21 oz. ), Small (18 oz.) and Peewee (15 oz. ). Extra Large, Large, and Medium are the sizes most commonly found in the market because they are the sizes hens most often lay.

1. Using lesson background information (and additional detail from lesson 7 background information), discuss egg grade and size standards with class.

2. Have students complete Eggs Make the Grade!

1. Invite a local egg producer or extension poultry agent to discuss egg production, egg processor to discuss egg processing or, if available, USDA grader or inspector to discuss grading and inspection services.

2. Have students break out raw grade AA and A eggs, record their observations about shells, whites and yolks and guess the eggs’ grades.

3. Have students peel hard-cooked grade AA and A eggs, estimate the likely size of their air cells based on the flattened ends and guess their grades.

4. Have students research how the USDA grades other foods.