After more than half of the candy has been removed,
gather the class together. Start the discussion by pointing out
that there is often great variation among individuals of animal
species. For example, students can look around the room and list
the characteristics that vary among humans. Then, ask the students
why variation is significant.
One reason variation is important is that variation
allows for differential survival of individuals. Show them the candy
bowl and the remaining candies. Count what candies remain and list
them on the board. Ask them if they remember which candies were
originally available. Make a list on the board of the original set
Now ask them to list the traits of the candy they
selected from the candy dish. (examples include: chocolate flavor,
large size, favorite brand, etc). These are the traits that led
to the removal of certain candies.
Make a list now of the traits of the candies that
were not selected (examples: bad flavor, small size). These are
the traits that allowed the candies to survive being passed around
So, the fact that there were different candies with
different traits resulted in some candies being eaten and others
surviving. This is what natural selection does with individuals
in a population. Each individual has unique traits; some traits
will help an individual survive and some traits do not.