Name:______

Natural Selection with Teddy Grahams

Purpose:

The concept of natural selection will be demonstrated

Materials:

Bears: Happy and Sad (Teddy Graham crackers)

Graph paper

Procedure:

  1. Ready the story and follow instructions.
  2. Obtain a population of bears (8-10), and record in table 1 the number of each: The Total Population, the Happy Bears, and the Sad Bears.
  3. Eat three Happy Bears. If you don’t have three Happy Bears, then eat what you have in Happy Bears.
  4. Get a new generation from the teacher. Repeat steps one and two.
  5. Repeat for two more generations (total of four).
  6. Determine the percentage of sad and happy bears for each generation (divide the number of that type of bear by the total number in that generation), record the percentages in table 2, and graph the population results.

Story:

You are a bear-eating monster from the land of Bear-Not-Friend. There are two kinds of bears that can be found naturally in your habitat: Happy Bears and Sad Bears. You can tell the difference between them by the way they hold their hands. Happy Bears hold their hands high in the air. They look like they have just scored a winning touchdown—if bears played football—American football—not Brazilian football. Sad bears hold their hands down low. They have not scored many touchdowns in football—if bears played football. Happy Bears taste sweet and are easy to catch. Sad Bears taste bitter, are sneaky, and hard to catch. Because of this, you eat only Happy Bears. New bears are born every ‘year’ (during hibernation). The birth rate is one new bear for every old bear left from the last year.

Hypothesis:

What do you expect to happen to the number of Happy and Sad Bears over time?

Results:

Number of bears at the start? ______This is generation one.

Table 1: The number of bears for each generation

Generation / Number of Happy Bears / Number of Sad Bears / Total Bears

Table 2: The percentage of bears for each generation

Generation / Percentage of Happy Bears / Percentage of Sad Bears / Total Bear Percentages

Graph the data from Table 2.

  1. Graph what happens to the bear population over time. (Follow the Example given)
  2. Include a key on your graph like the one below. Distinguish between the bears with a different color of crayon, color pencil, marker, or pen.
  3. Create your graph as a line, dot, or bar graph.

Key:

Graph Percentage of Happy Bears as:______(Use a color to distinguish)

Graph Percentage of Sad Bears as:______(Use a color to distinguish)

Conclusion:

  1. How many bears did you get for each generation?

Generation 1 _____

Generation 2 _____

Generation 3 _____

Generation 4 _____

  1. What happened to the percentage of each type of bear over time?
  2. Happy
  3. Sad
  1. How does this compare with your hypothesis?
  1. What is natural selection?
  1. Describe how happy and sad bears relate to the concept of natural selection.
  1. What is survival of the fittest? Does this lab demonstrate this idea which Darwin hypothesized? Explain.
  1. How does this lab demonstrate what occurs during natural selection in the wild? Write at least a paragraph summarizing your thoughts on this matter.