N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
Living Systems and Adaptations
A system can include processes as well as things. Learning about systems requires
understanding how parts relate to and influence one another. Systems often
contain other systems that may interact. There is interdependency of the
components within a system and therefore systems may not work when a part is
removed. Systems should be emphasized as students investigate the roles of
various organisms within an ecosystem.
Constancy and change are essential features of the natural world. As students
observe the world around them, they should look for evidence of what changes and
what does not change. Ideally, change should not be taught in isolation but
incorporated at every opportunity throughout the year in all units of science study.
Change influences systems. A very small change in a system can produce major
differences in what the system will be like in the future. For example, if one
organism in an ecosystem dies out, the ecosystem could change dramatically over
time.
In this unit of study, students explore the roles of various organisms in living
systems. By looking at the relationships that exist among organisms within a living
system, students understand that species depend on one another and on the
environment for survival. In previous grades, students have studied the
composition of various habitats and the interdependency of living organisms with
each other and with nonliving parts of ecosystems. A review of the relationships in
food chains and food webs would be appropriate: including relationships between
predators and prey; consumers and producers; and carnivores, herbivores, and
omnivores. Different species may live in the same habitat, but each one has a
specific role. The interaction of these organisms, each with its specific role, is one
factor that contributes to the overall health of the system. Students should
understand that if any part, living or nonliving, of the system is removed the
system may no longer function or begin to function in a new way. Students should
also gain understanding that organisms interact with one another in ways besides
providing food. For example, many plants depend on animals for pollination and
seed dispersal. This understanding will be enhanced as students learn about
adaptations of plants and animals.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
1
N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
Students should also understand that the source of energy in almost all
ecosystems is the Sun. (An exception is an ecosystem around a deep ocean vent,
which does not depend on the Sun for energy). Almost all food webs begin with
producers (plants). Plants capture light energy from the sun and use it to
manufacture food (sugars) from carbon dioxide and water through a process called
photosynthesis. Plants use the energy from this food to live and grow.
Energy is passed through an ecosystem as other organisms eat the plants, and
predators in turn eat them.
The arrows in a food web or food chain should always show the flow of energy
through a system. They should point from the organism being consumed to the
organism doing the consuming.
Example of a simple food chain with arrows showing energy flow
Organisms have two main types of traits: those that are inherited and those that
are learned. Inherited traits are passed from parents to offspring. Through
observation of actual organisms, pictures, or videos, students should notice that
offspring generally look like their parents. These traits include things such as fur
color, leaf shape, or number of legs. Some types of behaviors are also inherited.
These behaviors are called instincts, and organisms are born knowing how to do
them. For example, some birds are born knowing that they must migrate at various
seasons of the year.
Other types of behaviors are learned. For example, a child is not born knowing how
to play baseball. Through observation and practice he or she learns the rules and
skills of the game. Animals also learn behaviors. These learned behaviors usually
help them survive and are the result of living and non-living environmental
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
2
N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
influences. For example, a bird learns to avoid eating monarch butterflies by eating
one and becoming sick. Unlike animals, plants cannot learn. Students should keep
lists of things that animals and plants get from their parents and things that are
learned in order to distinguish between the two.
Inherited
Learned
The color of your eyes
Writing your name
A turtle's shell
A cow runs at the sound of a rattle snake
A flower's color
A tree growing an apple
Fish come to the top of the bowl when you
feed them
When the fire alarm sounds, we exit the
building
Leaves dropping from the tree in the fall
Your dog sits on command
Brown fur color
Brushing your teeth
Feathers as a body covering
Wrapping a package
In animals, traits acquired after birth are not passed on from parents to offspring
through heredity. For example, a dog that loses a leg due to an injury would not
have puppies without a leg. Some acquired plant traits are the result of human
manipulation. For example, a man may trim the bush in his yard to be a certain
shape, but without repeated trimming the plant would not keep this shape nor
would new plants have the trimmed shape. Other acquired traits may be due to
environmental influences. For example, trees can be bent by the wind, but their
offspring will not necessarily have the same shape if they are planted in a
different location.
If a species is to survive, individuals must reproduce and pass on their traits to
future generations. Adaptations are inherited traits that help a species meet its
needs and survive. The concept of adaptation and survival is focused at the species
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
3
N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
Living Systems and Adaptations (cont’d)
level rather than on individual organisms. A species is adapted to its environment
when an inherited trait helps the species survive there. For example, a snowshoe
hare is white in the winter and brown in the summer. This adaptation helps this
species survive in its seasonally changing environment. Adaptations may cause a
system to change because they may increase the survival of one particular species
over another, causing the balance in the system to shift. Changes in the
environment may cause the natural variation in organisms to become an advantage.
For example, jackrabbits live in a sandy, rocky habitat with some dry grasses. A
jackrabbit may have several babies, five brown and one white. The baby rabbits
with brown fur will blend in with their habitat very well and will be more likely to
survive. The white baby rabbit will be more easily seen by a hungry fox and
probably will not survive to pass on white fur to any offspring. Over time there may
be significantly more brown jackrabbits in this habitat. However, if the habitat and
climate were to change and become snow covered, the trend would be reversed.
The white baby rabbits would now have the advantage and be able to survive better
because the hungry fox would notice the brown baby rabbits more easily. The
number of white rabbits would increase and the number of brown rabbits would
decrease. This could lead to a change in the species, after many generations that
would include almost all white rabbits.
Some inherited traits only become noticeable when triggered by environmental
changes. For example, a wolf will develop a thicker coat in the winter that helps
protect it better from the cold temperature than its thinner summer coat would.
Also, most trees have root systems that respond to available water. These trees
may develop deeper root systems to reach a water source. These changes are
inherited abilities that are triggered by the environment in which the organisms
live. Students should identify adaptations in a variety of species of both plants
and animals.
By comparing the adaptations of various species, students can develop
generalizations about the kinds of adaptations predators have (offensive tools
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
Living Systems and Adaptations (cont’d)
such as teeth, beaks, claws, venom, etc.) and those that prey have (defensive tools
such as camouflage to hide, speed to escape, shields or spines to ward off,
irritating smells to repel, etc.). This comparison could also lead students to
understand that animals are placed into groups based on their similarities and
differences.
Some Types of Adaptations
Purpose of
the
Adaptation
Examples

Getting Food


Protection

Eagles have sharp beaks that they use to tear apart small
animals.
Female mosquitoes use their straw-like mouthparts to suck
blood.
Rosebushes have thorns that help protect them from planteating animals.
When skunks are threatened, they can spray a bad-smelling
liquid onto their enemies.
The seeds of coconut palm trees float on water and can be
carried from one island to another by the ocean.
Reproduction

Water
Conservation


Lizards have scaly skin that prevents water loss.
Some plants have small leaves to prevent water loss.

Fish have gills that they use to take oxygen from the water
in which they live.
A whale breathes air through a single nostril on top of its
head when it comes to the ocean’s surface.
Getting
Oxygen

These groups have adaptations in common and show the great diversity of life that
is able to survive on Earth. Students were introduced to the idea of scientific
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
5
N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
classification, at a very fundamental level, in second grade as they looked at the
external characteristics and their functions of various animals and plants. In
fourth grade it would be appropriate for students to extend their knowledge of
these groups. The chart below includes the characteristics that these groups have
in common. Students should focus on the commonalities, rather than memorizing
the names of these groups. A more in depth classification (i.e. Kingdom, Phylum, or
Species) is not appropriate at the elementary level.
Characteristics (adaptations)























Fur or hair
Warm-blooded
Live birth
Nurse and care for their young
Breathe through lungs
Feathers
Warm-blooded
Hatch from eggs
Breathe through lungs
Scales and dry, thick skin
Cold-blooded
Breathe through lungs
Most hatch from eggs
Scales
Cold-blooded
Gills to breathe in water
Most lay eggs, a few snakes have live
birth
Moist, thin skin
Begin life in water with gills
Develop lungs as an adult
Adapted to live on land and in water
Cold-blooded
Hatch from eggs
Vertebrate
Group
Mammals
Birds
Reptiles
Fish
Amphibians
Examples




Bear
Elephant
Whale
Dog












Eagle
Hawk
Woodpecker
Vulture
Turtle
Snake
Lizard
Crocodile
Goldfish
Catfish
Tuna
Salmon




Frog
Salamander
Newt
Toad
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
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N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
Students should also understand the major adaptations of plants that scientists
use to classify them into groups. A diagram follows to outline these commonalities.
Plants
Non-seed Plants
(Spores)
Mosses
Ferns
Seed Plants
(Seeds)
Flowering Plants
Conifers
Most organisms change in several ways throughout their life cycle. Some organisms
are born looking like a smaller version of the adult they will become, and their
outward appearance changes very little as they grow. A grasshopper is an example
of this type of organism. Other organisms have major changes in body form as they
go through their life cycle. This is called metamorphosis. Butterflies are an
example of organisms that go through this dramatic set of changes: egg, larva,
pupa, and adult. A frog changing from a tadpole with gills to an adult frog with
lungs is another example of this type of change. All of these processes are one
more amazing way for students to understand the diverse ways organisms are
adapted to survive on Earth.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
7
N o r t h E a st I n d ep en d e nt S c h o o l D i st ric t – 4 t h G rad e S ci en c e
Living Systems and Adaptations Unit 2 Clarifying Statements Rev. May 2006
2006
Note: Many campuses use the Constancy and Change Vistas, which contain lessons
on either lifecycles or adaptations. The Vistas suggest the following organisms
(focus is indicated in parenthesis):
Kindergarten – Ladybugs (life cycle)
3rd Grade – Frogs (adaptations)
1st Grade – Mealworms (life cycle)
4th Grade – Bats (adaptations)
2nd Grade – Butterflies (life cycle)
5th Grade – Brown Pelican
(adaptations)
Dissections are not recommended for elementary students.
Fossil records help scientists know about the relationship between species of the
past with those of the present. Fossils are any part of a once-living organism that
is now preserved in the Earth’s rocks. By comparing fossils to one another and to
living organisms, students can conclude that some organisms living today are similar
to those that lived long ago and may share a common ancestor, but also that some
organisms are very different. These similarities and differences suggest that
organisms have changed over time. The structures that exist in organisms today,
that are very similar to the structures in organisms of the past, are most likely
structures that gave the organism a better chance of survival. Because these
organisms survived, they passed on these characteristics to their offspring. Other
structures, which no longer exist in present day organisms, were probably not an
advantage to the organisms’ survival. Therefore, not many of the organisms with
those traits were able to pass them on to offspring, because organisms with those
traits did not survive. Over time, this leads to changes in species of living
organisms.
Clarifying statements are intended to deepen teachers’ understanding of science concepts and serve as a guide for
instructional design. They are not intended to serve as student instructional materials.
This publication is the property of North East Independent School District. Duplication in whole or in part, outside of NEISD, is
prohibited without express written permission from NEISD.
8