Populations are groups of organisms that live in the same ecosystem.  When different populations live together it is called a community.  Communities are made up of living things, but these living things interact with non living things in ecosystems.  Scientists take samples of different ecosystems to determine what kinds of organisms live there.  However, sometimes scientists don't see everything that is in an ecosystem.  When you look outside do you see everything that is in your ecosystem?

Today you are going to be ecologists sampling an ecosystem to see what kinds of organisms live there.  Ecology is the study of the relationship between organisms and their environments.  If you follow the directions carefully and answer all of the questions then you will understand and enjoy the science of ecology better.

Write all information on the back of this lab paper

1.    Choose an ecosystem that you would like to sample.  Some examples include forest ecosystem, marine
        ecosystem, tundra ecosystem, desert ecosystem, tropical rain forest ecosystem, grassland
        ecosystem, urban ecosystem, rural ecosystem, tropical ecosystem, marsh/swamp ecosystem, etc.
2.    Write down six (6) organisms (living things) that you could find in your ecosystem.  Try to list
        plants as well as  animals.  Assign a color to each organism (red, orange, yellow, green, blue, and
        brown) and write them in the space provided on the lab worksheet.
3.    Open one bag of "M&M's" and pour them on the lab table.  Count the number of each color that you have and write it
        down on your lab worksheet under 'Total in Population'.
4.    Put all "M&M's"  in the brown paper bag and shake them up.  One at a time, draw out an "M&M" and put a tally
        mark in the corresponding box titled 'Samples' (you might want the person who is going to eat the "M&M's" to be the
        one who touches them).  Make sure to put the "M&M" back in the bag before drawing out another "M&M".
5.    Keep drawing "M&M's" until you have completed 100 draws.  Nest, total how many of each color you drew in the box
        marked 'Total in Samples'.  One person needs to write on the board your results for class data.
6.    You can eat the "M&M's" now.
 
 

Color of "M&M"	Organism	Total in Population	Samples	Total in Samples
Red
Orange
Yellow
Green
Blue
Brown
TOTALS	6	Variable	100	100

 

Questions

1.    Did you see each organism in your ecosystem?

2.    Did you see any organism more than the others?  If so, which organism did you see the most?

3.    What is the chance that you will see the organism with the smallest original population (show your
        work)?
 
4.    Would taking more samples give you a better representation of the organisms in your ecosystem?
        Explain.
 
  5.    If you didn't have as many organisms in your ecosystem, what do you think would happen to the
        diversity?  Would this affect the balance of the ecosystem?
 
  6.    What is one thing you have learned about by doing this lab?
 
Teacher Notes

-Show the students how to make tally marks up to the number five (5)
-Review calculating percentages.  For upper level classes you may wish to introduce advanced methods of
    analyzing the data, such as the Hardy-Weinberg equation, Mann-Whitney u-test, or Analysis of
    Variance (ANOVA).
-Add your own variations to this activity

1.    Did you see each organism in your ecosystem?

        Students should have seen each organism at least once.

2.    Did you see any organism more than the others?  If so, which organism did you see the most?

        Due to the increased number of individuals in certain populations students should have seen some
        organisms more often than others (most likely the organism assigned to the color brown since it is
        represented the most in the bag of "M&M's" .  See graphs above).  Students should list these
        organisms.

3.    What is the chance that you will see the organism with the smallest original population (show your
        work)?
 
        Students need to convert the 'Total in Samples' number to a percentage (they should first locate
        the smallest original population and then convert that population's 'Total in Samples' to a
        percentage).

4.    Would taking more samples give you a better representation of the organisms in your ecosystem?
        Explain.

        Yes.  The more samples you take, the better the chance of seeing each organism.

5.    If you didn't have as many organisms in your ecosystem, what do you think would happen to the
        diversity?  Would this affect the balance of the ecosystem?

        The fewer the organisms, the less the diversity---for example, if there were no wolves to eat the
        rabbits, how many rabbits would there be on earth?  The balance of the ecosystem would have
        changed.

6.    What is one thing you have learned about by doing this lab?

        Answers will vary.

Activity and web page prepared by:

Marlies Navalta
Rancho High School
1900 E. Owens Ave.
Las Vegas, NV  89030

Woodrow Wilson Leadership Program in Environmental Science lpt@www.woodrow.org
The Woodrow Wilson National Fellowship Foundation webmaster@woodrow.org
CN 5281, Princeton NJ 08543-5281 Tel:(609)452-7007 Fax:(609)452-0066