Copyright © The Norwood Science Center 2005
The Norwood Science Center
Animals
Grade 4
Background Information:
Every living thing, whether plant or animal, must have food to
live. Plants manufacture their own food from carbon dioxide, water
and sunlight, but animals must eat plants or other animals to survive.
One could represent the relationship between a mouse and grass as
follows:
Grass----->Mouse
meaning that grass is eaten by the mouse. The mouse, in turn, is
eaten by an owl, which could be represented as
Grass---->Mouse---->Owl
This simple progression has been termed a Food Chain. In
most ecosystems, however, the arrangements are not this simple.
The owl eats other animals in addition to the mouse and some of
these animals that are prey items of the owl might also prey upon
mice. This arrangement might be represented as:
owl
chameleon
fox
mouse
seeds
cricket
grass
Web of Life Gr. 4 07
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As you can see from the previous illustration, an ecosystem can
have several Food Chains. Many organisms eat more than one kind
of food. As a result, the Food Chains overlap. These overlapping
Food Chains form a Food Web.
There are certain roles each organism plays within an
ecosystem. Plants are known as Producers because they convert
the Sun's energy into a form of energy animals can use. The
organisms that feed only on plants are called First-Order Consumers.
Organisms that feed on animals are called Second-Order
Consumers. It is very important to notice that most Consumers are
involved in several Food Chains since most consumers eat more than
one kind of food. As a result, Food Chains can overlap.
Decomposers (bacteria and fungi) enter the Food Chain when
producers and consumers die. Decomposers help return the remains
of these organisms to the soils where they will provide nutrients for
future plants.
TITLE:
THE WEB OF LIFE
PURPOSE:
Create paper models of Food Webs
MATERIALS:
(per pair of students)
One Web Of Life Worksheet #1
Pencils
Rulers
Four crayons: green, orange, red, and brown
PROCEDURE:
01.
Introduce students to the terms Producer (P), First-Order
Consumer (C1), Second-Order Consumer (C2), and
Decomposer (D) and the respective roles of each in the
ecosystem.
02.
Arrange students in pairs.
03.
Distribute a single The Web Of Life Worksheet #1 to each pair.
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04.
The students are to identify the ecosystem role of each of the
organisms on the worksheet. They should place the
appropriate code next to the circle. Check results with the
class.
05.
Once the students have completed the correct coding, they
should color in the circles using the following sequence:
Producer = green; First-Order Consumer = orange; SecondOrder Consumer = red; and Decomposer = brown.
06.
The students are to find one organism that consumes another.
They are to draw a rulered line between the two circles.
07.
Placing an arrowhead on the end of the line towards the
consumer doing the eating will help give the web direction.
08.
Students are to draw in every line they can imagine that reflects
a food-consumer relationship.
09.
Once the students have completed the work they should be
polled as to their reactions regarding the Food Web.
10.
Pose the following questions:
a.
If there were no more mice, what would happen to all the
components of the Food Web?
b.
If there were no more earthworms, what would happen to
all the components of the Food Web?
Extension:
01. Distribute the Web Of Life Worksheet #2.
02.
Students are to write in the names of types of producers and
consumers they might see in their neighborhood.
03.
Students are to repeat the activity from the lesson on the
previous page with the new Web.
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Copyright © The Norwood Science Center 2005
CONCLUSION:
01. Ask the students why Food Webs are found in nature rather
than Food Chains.
SOURCE:
01. Food Chains and Webs, Delta Science Module, Delta
Education
Web of Life Gr. 4 07
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Copyright © The Norwood Science Center 2005
Grass
Bacteria
Owl
Flower
Worm
Mouse
Fox
Butterfly
Web Of Life
Worksheet #1
Web of Life Gr. 4 07
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Copyright © The Norwood Science Center 2005
SUN
Grass
P
Bacteria
Owl
D
2C,3C
Flower
Worm
P
1C,2C,3C
Mouse
Fox
1C
2C, 3C
Butterfly
1C
Web Of Life
Worksheet #1
Web of Life Gr. 4 07
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Copyright © The Norwood Science Center 2005
Web Of Life
Worksheet #2
Web of Life Gr. 4 07
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