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WHAT IF THE POPULATION POPS?
MASTER TEACHER Jeff Duffy
GRADES 6 - 8
OVERVIEW
This lesson is designed to acquaint or reinforce student
knowledge about populations and the natural consequences of dynamic
populations. Viewers will be able to calculate the growth of unrestricted
populations, chart this growth, and predict what might occur with successive
generations. They will also be able to describe various biological groups such
as herbivores and carnivores as well as moral and ethical issues dealing
with (over)population.
ETV
Bill Nye the Science Guy #207 - Population
LEARNING OBJECTIVES
Students will be able to:
*Describe and calculate the properties of reproduction
*Identify the basic factors that regulate population changes
*Suggest options for population regulation
*Relate various life forms and how they impact the growth of one
another
*Graph a growing population and predict future numbers
MATERIALS
Worksheet for calculating population growth
Chart to predict population expansion
Ticky-tacky to fasten vocabulary words to TV cart
VOCABULARY
Carnivore-an animal that eats meat
Competition-condition that arises when demand is greater than
supply
Herbivore-an animal that eats plants
Omnivore-an animal that eats meat and plants
Parasite-an organism that relies on a living host for its
existence
Population-group of like organisms in a specified space
Habitat-specific place and conditions where a population lives
Endangered -situation when the continued existence of a species
is in doubt
PRE-VIEWING ACTIVITIES
Have students identify some of the problems that they are aware
of in their school or community or in the world. Direct them toward the
idea that many problems occur when there is an increasing number of certain
things, such as people, or rats, or mosquitoes, etc. (or customize the
discussion to fit a situation appropriate for your area) Have the
students record their answers on the worksheet provided.
FOCUS FOR VIEWING"Have you ever noticed after a summer
rain that the air is soon choked with mosquitoes. Where were they before the
rain, and where are they some days after the rain?" To give the
students a focus for viewing, we are going to look at some of the factors that
might explain why the number of mosquitoes, and in fact, all living things, are
always changing.
VIEWING ACTIVITIES
Begin the video where Bill is working a crossword puzzle. As the
introduction runs, tell the students they will work a puzzle at the end of the
lesson. Bill describes several populations. Pause Bill looks through a
microscope, then stands up. He says, "There are populations
of things you can't see with the naked eye." Give students an opportunity
to name other populations. All answers should contain the same type of organism.
Responses such as "farm animals" or "birds" should be
refined to be more specific, such as domestic dogs, doves, Herefords, or field
mice. After five or six responses, say, "What might happen if these
populations add extra members?" Resume Bill discusses the effect of
increasing the population. Pause Bill pokes his head out a the box
of rubber balls and says, "I'm OK." Have students give ideas where
overcrowding occurs. Encourage them to think beyond animals. Too many
weeds, too much bread mold, too few fish, etc. After five or six responses, ask,
"Does anyone know what a population of fish is called (school), a
population of birds (flock)?" After responses, say, " Listen carefully
to the next part of the video and you will see that there are lots of special
names for different populations. Some may be in your puzzle at the end of this
lesson." Resume Bill gives the names of various populations and then
his assistant examines the reproductive rate of populations. Pause
When the calculator screen shows "256". There is no audio at this
pause point. Have students fill in the remainder of the calculations on their
worksheet. Have them stop after ten "generations". When all have
finished and their calculations checked, ask, "Can this increase go on
forever?" Say, "Let's see what Bill and his assistant have to
say." Resume Bill discusses the world's population when he was
a kid, the current population, and the projected population for humans.
Pause Richie's mom says, "...survival as a population
as well as a family." Richie shoves a slice of bread into his mouth."
Ask the students, " Can you think of any problems that you , your school,
or your community have because of an increasing population?" Write them in
the space provided on your worksheet. When students finish ask, "What
keeps populations from getting larger and larger? Let's find out."
Resume Segment discusses the role of food chains and
population cycles. Pause Narrator says, "…and a
subsequent rise in the population and the cycle begins again," and the
video segment show the rabbits just as they finish eating the last of the grass.
Ask the students, "What factors affect the changes in a population?"
The factors are reproductive rates, availability of resources (food, shelter),
and natural enemies. After students identify these, ask, "Does an
animal as small and 'simple' as a bee have problems with population control?
Let's take a look." Fast Forward to the second time
"Way Cool Scientist" title appears and turns to a TV
screen. There is no audio signal here. Resume This segment
deals with population control by observing bees. Pause Boys take honey
from a jar and "Check It Out" comes to the screen. The boys say,
"Bee barf is the best." Ask the students, "Why did more of
the wooden frames have to be added to the hive?" (Make room for more bees).
Ask why the "outsider" was at the hive (looking for a place to live).
Ask if other populations compete for space, food, shelter, etc. Say,
"Do humans compete for these kinds of resources? Let's see if Bill
has any ideas." Resume This segment deals with human
population increases and population curves. Pause Bill looks up after the
girl has eaten all of his grapes and says, "What happened to all the
grapes?" Use the information generated at the beginning of the lesson
(population data) and prepare a graph using the form on the worksheet. Have
students plot data for at least ten generations. Have them predict what will
happen to the curve for successive generations. Ask , "What, if
anything, will stop this rise in the human population, and what is happening to
other populations?" Student responses may include overcrowding, starvation,
extinction, adaptation, etc. When adequate responses have been fielded,
say, "What does man do to his environment and what happens to other species
as a result?" Resume This section deals with habitat destruction and man
modifying his environment. Species endangerment and extinction result.
Pause A bus passes behind Bill and he says, "Where's everybody going?"
Review causes of overpopulation and have students name some endangered species.
Solicit ideas on how to protect these organisms. When finished, say, "Let's
summarize today's activities with a song." Resume Stop
Song ends and credits roll.
POST-VIEWING ACTIVITIES
Say to the students, "Now that you have had a chance to
view the basics of population dynamics, let's see how much you remember. Here is
a crossword puzzle that covers information from the video. You may also have to
make inferences or visit other sources to find all of the answers."
ACTION PLAN
Arrange a visit from a Parks and Wildlife ranger to discuss how
hunting and fishing quotas are determined
Discuss possible explanations of why some species have become
extinct.
Visit area zoos and study the plight of endangered species.
Examine the effects of modern medicine and diet on the longevity
of humans and the impact that longer lives has on population.
Visit websites such as .
http://mthwww.uwc.edu/wwwmahes/courses/geog/350/pop.htm http://www.jhuapl.edu/colloq/popgroth.htm
http://home.worldonline.nl/~quark/index.html http://www.fws.gov/r9endspp/kid_cor/heyteach.htm
EXTENSIONS
Mathematics
Project population growth from graphs.
Display large populations using scientific notation.
Calculate population densities using area and number of
inhabitants.
Social Studies
Research which countries are experiencing the fastest, or
slowest, population growth.
Discuss why populations of humans continue to rise while others
fall.
Examine economic aspects of population fluctuations.
Health
Study reasons why modern man is living longer than every before
and how this affects population growth.
Study the health impact on animal and plant populations as they
are forced to share closer and closer living quarters.
Science
Investigate modern techniques of manipulating reproductive
and survival rates of various organisms.
Research possible strategies for accommodating an increasing
population such as increasing crop yields, acquiring additional fresh
water, and maintaining a healthy atmosphere.
Identify endangered species at a local and global level.
Art
Design posters stressing the importance of maintaining a
population growth the planet can support.
Have a contest depicting the plight of endangered species.
Updated: April 01, 2008
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