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Population numbers themselves mean nothing unless they can be compared with numbers from other populations. Since most areas where organisms are found are of unequal size, density must be used instead of total population for proper comparison. Example: Maryland and Missouri both have a population of almost 5 million. But Missouri is about 7 times larger than Maryland. Also, the populations of Maryland and Missouri have changed over the last few decades. This lesson will allow the student to calculate both population densities and rates of density change.

When students have completed this activity, they will be able to:

1. Calculate the density of a population.

2. Calculate the rate of change for a population.

STRATEGIES

1. Formulas: 

                                                         N (Number of organisms)

                                             (Density) D = ---

                                                                      S (Size of area)

                                                                   D D (Change in density)

                              (Rate of Change) R = -----

                                                                   D T (Change in time)

2. Have students calculate the density of various populations.

Some suggestions for study populations include:

a. Students in the classroom.

b. Students per room in the school.

c. Various populations from an almanac.

d. Plants on the school campus.

e. Acorns produced on oak trees on the school campus.

3. Review methods of calculating area. Use either a Quadrant, 1.5 m x 1.5 m, or a Transect, 3 m line measuring 0.3 m to either side of the line works.

4. Have students calculate the rate of density change. The almanac is a good source of population change over time. You can also compare the density of your school over various years. Construct your own work sheets and population sheets.

5. Optional: Using earlier calculations, have students predict populations for future dates. Ex. What will the density of your school be in the year 2000? Interesting discussions on the effects of this populations increase or decrease can occur.

       The Forest Conservancy District Board for Baltimore County

9405 Old Harford Road

Baltimore, Maryland 21234

(410) 665-5820 

Email Robert Prenger ....... rprenger@dnr.state.md.us

 Melvin Noland ....... mlnoland@bcpl.net