NATURAL SELECTION LAB: HAPPY AND SAD TEDDY GRAHAMS
BACKGROUND INFORMATION:
Teddy Grahams (now Dizzy Grizzly’s) are little graham crackers that come in the shape of bears. On close
inspection one will notice that the crackers in the box come in two shapes: with their hands up, and with their
hands down.(or on wheels or without wheels) They crackers present themselves as a population with members
possess one of two possible observable forms of a trait. This makes them very convenient to use in a natural
selection activity.
Preparation for Natural Selection with Teddy Grahams requires either the purchase of Teddy Graham crackers,
or photocopying and cut out of paper bears to simulate the crackers. Amount of crackers is dependent on
number of students in class, average about two - three boxes per class. Preparation of a lab involving food
consumption should also be considered.
Students need only a writing instrument and graph paper to complete lab. Class time needed is one hour class
period with possible additional time for completion of graphs and questions.
Summary/Abstract:
This lesson provides student/groups with insight into the effect on a population from the process of natural
selection. Data is gathered on the appearance of two phenotypes over successive generations as a specific
selective force is applied. Students graph phenotype percentages to provide a visual representation of data
collected during procedure. Story set-up and cracker "prey" place student in the center of activity as the
selection pressure.
Materials:
Bears: Happy and Sad (Teddy Graham crackers)
Procedure:
1) Read the story and follow directions.
2) Obtain a population of bears, 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 (devide 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. There are two kinds of bears: 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, and
Sad Bears hold their hands down low. 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) obtain another handful of bears if two or more are left in your population from the previous
generation.
NATURAL SELECTION LAB: HAPPY AND SAD TEDDY GRAHAMS
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
# of Happy Bears
# of Sad Bears
Total Bears
1
2
3
4
Table 2: The percentage of bears for each generation
Generation
% of Happy Bears
% of Sad Bears
1
2
3
4
1) Graph what happens to the bear population over time.
Key:
Graph Percent of Happy Bears as: ________
Graph Percent of Sad Bears as: ........
Conclusion:
1) How many new bears did you get for each generation?



Generation 2 ____
Generation 3 ____
Generation 4 ____
2) What happened to the percentage of each type of bear over time?
a. Happy?
b. Sad?
3) How does this compare with your hypothesis?
4) In your own words, describe what happened in your graph.
5) What is natural selection?
6) Did natural selection occur? State your claim, evidence, and reasoning.
Claim
Evidence
Reasoning
7) What other types of things can limit how the teddy grahams survive and reproduce? (Hint: Think about
things the teddy grahams will need.)