T E A C H E R ’ S G U I D E
T E A C H E R ’ S G U I D E
T E A C H E R ’ S G U I D E
22. How do food chains join to form food webs?
I n t e rnet Resourc e s
23. Why are food webs more accurate and complex than food chains?
Periodically, Internet Resources are updated on our web site at
24. How can human actions upset the balance of an ecosystem?
The “Webs of Life” pages of the Dragonfly Web site investigate the
R e s e a rch indicates that students will retain their previous misconcep-
intricate network of plants & animals that depend upon one another
tions about a topic, in pre fe rence to new info rm a t i o n , until they
actively recognize and correct their own errors. Therefore, it is impor-
tant to have your students re - examine the facts/beliefs they put on
their “ E ve rything We Think We Know A b o u t … ” l i s t . It might also be
This advanced site has excellent illustrated food webs and ecological
pyramids for many different ecosystems.
helpful to rev i ew the list by marking each entry with a “ + ” or “ - ” t o
show which facts were correct and which were incorrect.
Discussions that ensue from thought-provoking questions provide a
This game by EcoKids allows students to build a food chain and then
good way to assess the ove rall depth of student unders t a n d i n g . T h e
see what happens when one link is removed from that chain.
following are some suggested discussion questions.
1. Explain the meaning of this statement: “If it we re n ’t for the gra s s
Suggested Print Resources
and all the other green plants, you wouldn’t be around.”
• Crenson,Victoria. Horseshoe Crabs & Shorebirds: The Story of a Food
Web. Marshall Cavendish,Tarrytown, NY; 2003.
2. Discuss the fact that energy in a food chain is not created or
Students in grade 5–8 cl a s s rooms possess a wide ra n ge of
b a ck ground know l e d ge . Student response to this video
destroyed but only transferred from organism to organism.
• Greenaway, Theresa. Food Chains. Raintree Steck-Vaughn, Austin,TX;
p ro gram is sure to be va ri e d , so the teach e rs for these
3. Discuss how any small ch a n ge in an ecosystem will affect all the
grades need all the help they can get! This guide has been
other parts of the food web.
• Kalman, Bobbie. Desert Food Chains. Crabtree Publishing Company,
designed to help science teach e rs in grades 5–8 by prov i d-
New York, NY; 2004.
ing a brief synopsis of the pro gra m , p re - v i ewing and fo l l ow -
TEACHER’S GUIDE CONSULTANT
up questions, a c t i v i t i e s , vo c ab u l a ry and additional re s o u rc e s .
• It is important for students to realize the importance of every single
Conrad M. Follmer
B e f o re Vi e w i n g : E x t e n s i ve re s e a rch tells how import a n t
p a rt of a food ch a i n . Discuss the implications of food chains whose
25 years as a K–5 Science & Math Coordinator for a Pennsylvania public
it is for the teacher to discover what the students know —
balance has been upset. S p e c i fic examples to consider are the era d i-
school system, currently an independent consultant to elementary schools.
or think they know — about a topic, b e fo re actually start-
cation of mosquito populations, re m oving top pre d a t o rs from an
ing a new unit.T h e re fo re , after prompting discussion with
ecosystem and killing plants with pesticides.
• ENDANGERED &
the pre - v i ewing questions, lead your class to create a
• ANIMAL ADAPTATIONS
“Everything We Think We Know About…” list.You may also
• In small gro u p s , h ave students create three-dimensional food ch a i n s
• ANIMAL BEHAVIOR &
by using plastic animals, modeling cl ay, e t c . C h a l l e n ge the whole
wish to prev i ew key vo c ab u l a ry wo rd s , and have students
raise additional questions they hope will be answered.
class to create a food web with more than 75 organisms by linking
• ANIMAL CLASSIFICATION
• FOOD CHAINS
their food chains appropriately.
• ANIMAL INTERDEPENDENCY
• INSECTS & OTHER ARTHROPODS
After Vi e w i n g : H ave your students share video ex c e r p t s
• Initiate a discussion on the importance of decomposers to the env i-
• ANIMAL LIFE CYCLES
that fascinated or surprised them, then ch a l l e n ge your stu-
• ANIMAL NEEDS
• MARINE & OTHER INVERTEBRATES
ro n m e n t . H ave students imagine an Earth without decomposition and
dents to prove or disprove the accuracy of the facts they
w rite a short essay depicting the pro blems faced in such a situation.
put on their “ E ve rything We Think We Know A b o u t … ” l i s t .
Discuss what else they learned and use the fo l l ow-up ques-
• Have individuals or small groups research the following concepts:
Teacher’s Guides Included
and Available Online at:
tions and activities to inspire further discussion. E n c o u rage
— Ecological energy pyramid & trophic levels.
students to re s e a rch the topic further with the Internet and
— The work of decomposers.
reading re s o u rces prov i d e d .
— The nitrogen cycle.
Teacher’s Guide and Program Copyright 2000 by Schlessinger Media,
— The role of abiotic (non-living) factors in an ecosystem.
a division of Library Video Company
P.O. Box 580, Wynnewood, PA 19096 • 800-843-3620
Executive Producers: Andrew Schlessinger & Tracy Mitchell
Programs produced and directed by Burrud Productions Inc.
All rights reserved
p h o t o s y n t h e s i s — The process of using wa t e r, carbon dioxide and
• H ow is the sun’s energy passed along from organism to organism in
P rogram Summary
sunlight to produce sugars.
E ve ry living thing uses energy that fl ows from the sun. When a mouse
chlorophyll — The green chemical in plants that traps the sun’s energy
• What is a food chain? Where do humans fit into food chains?
eats gra s s , it gets energy.Then a snake eats the mouse and gets energy.
so photosynthesis can take place.
E ve n t u a l ly, the snake dies and its body becomes a source of energy fo r
After the class has completed their “ E ve rything We Think We Know
herbivores — Animals that eat only plants.
insects, fungi and microscopic creatures.This energy transfer from organ-
About…” list, ask them what other questions they have that they hope
ism to organism is called a food chain.
primary consumers — Herbivores; plant-eating animals that get energy
will be answe red during this pro gra m . H ave students listen cl o s e ly to
from consuming plants.
All life is dependent on plants as the fi rst link in the food ch a i n . P l a n t s ,
l e a rn if eve rything on their class list is accurate and to hear if any of
carnivores — Animals that eat other animals.
also called pro d u c e rs , m a ke food and ox y ge n .T h rough a process called
their own questions are answered.
p h o t o s y n t h e s i s , p ro d u c e rs trap the sun’s energy and make it ava i l able to
secondary consumers — Animals that get the sun’s energy indire c t ly
a n i m a l s . Animals are called consumers because they must eat, o r
by eating other animals.
c o n s u m e , to get energy.This energy is then tra n s fe rred throughout the
omnivores — Animals that eat both plants and animals.
1. H ow is energy from the sun passed from one organism to another
ecosystem in food ch a i n s . Plant-eating animals, also called herbivo re s , a re
p re d a t o r — An animal whose food is pri m a ri ly obtained by the killing
in an environment?
c o n s i d e red pri m a ry consumers because they get their energy dire c t ly
and consuming of other animals.
2. W hy is photosynthesis so critical to the surv i val of eve ry living
f rom plants. Meat-eating animals, also called carn i vo re s , eat herbivo res or
prey — Animals that are eaten by predators.
other carn i vo re s . T h ey get their energy indire c t ly from plants and are
scavengers — Animals that feed on dead animals.
3. What is chlorophyll?
k n own as secondary consumers . D e c o m p o s e rs are the insects, b a c t e ri a
d e c o m p o s e r s — Organisms like insects, b a c t e ria and fungi that bre a k
and fungi that break down the remains of all plants and animals, re t u rn-
4. What is the relationship between pro d u c e rs and consumers in a
down dead plants and animals, returning nutrients to the soil.
ing some of the sun’s energy to the soil. In this pro c e s s , carbon diox i d e
e c o s y s t e m — The relationship among all of the living and non-living
and nitrogen are released, and other nutrients are deposited in the soil for
5. What is an example of a producer in a food chain?
elements in an environment.
use by pro d u c e rs , s t a rting the cycle all over ag a i n . This is called the
6. What are some examples of consumers in a food chain?
p h y t o p l a n k t o n — Ti ny green plants that make up the bottom “ p ro-
ducer” level of marine food chains.
7. W hy are some consumers called pri m a ry and others called
We can track the flow of energy through an ecosystem by looking at food
Charles Elton — (1900-1991) The ecologist who calculated the biomass
ch a i n s . The greatest concentration of energy is in the plants. P ri m a ry
of ecosystems and, in 1927, came to the conclusion that there was fa r
8. Are omnivores classified as primary or secondary consumers? Why?
c o n s u m e rs , the herbivo re s , use about 10% of the energy that plants
greater biomass at the lower levels of a food chain than at the top. H e
9. Is this statement true or false: All predators are secondary
produce. Secondary consumers, the carnivores, use only about 10% of the
observed that these numbers formed an energy pyramid.
consumers, while all prey are primary consumers? Explain.
e n e rgy in the herbivo re s , so they must eat more to get the same amount
t rophic levels — Diffe rent steps in a food chain of an ecosystem.T h e
10. What is the role of scavengers in an ecosystem? Give an example of
of energy. Because the energy flow from one level to the next is less and
o rganisms of a chain are cl a s s i fied into these levels on the basis of their
less, animals at the top of the food chain must eat the most. An ecological
feeding behavior.The first and lowest level contains the producers, green
e n e rgy py ramid illustrates the fact that it takes an enormous number of
11. What is the role of decomposers in an ecosystem? Give an example
p l a n t s . Second level organisms are the herbivo re s , or plant eaters .
small animals to sustain fewer nu m b e rs of large animals. Animals are
O c c u pying the third trophic level are the carn i vo res that feed on herbi-
of a decomposer.
cl a s s i fied into diffe rent steps on the py ramid according to their fe e d i n g
vores.The smallest and highest trophic level contains predators that feed
12. What is the “nitrogen cycle”?
behavior. These steps are called trophic levels.
on other predators. In all the trophic levels, only 10% of the energy in one
13. What is the definition of ecosystem?
Because many animals within an ecosystem share the same fo o d , fo o d
level is passed to the next.
14. G i ve an example of a terre s t rial food chain that has at least fo u r
chains connect into complex food we b s . When an ecosystem is in
biomass — The total weight of all creatures in each trophic level of food
b a l a n c e , all organisms have sufficient energy and food to surv i ve . W h e n
15. Give an example of an ocean food chain with at least four links.
an imbalance occurs, every organism in the food web suffers.
food web — The complex feeding relationships among all the cre a t u re s
16. Why are tiny plankton so important to marine ecosystems?
in all the food chains of an ecosystem.
17. What is the ecological energy pyramid?
Vo c a b u l a r y
The fo l l owing wo rds are included for teacher re fe rence or for use with
P re-viewing Discussion
18. What are trophic levels?
students. They are listed in the order in which they appear in the video.
B e fo re students ge n e rate their list of “ E ve rything We Think We Know
19. What did the ecologist, Charles Elton, contribute to our understand-
food chain — The path that energy takes as it passes from organism to
About…” for this topic, stimulate and focus their thinking by raising these
ing of ecosystems?
organism within an eycosystem.
questions so that their list will better reflect the key ideas in this show:
20. What is biomass?
p ro d u c e r s — Organisms that use the sun’s energy to make fo o d . P l a n t s
21. What happens to the amount of energy that is transferred from one
trophic level to the next?