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Structures

Processes

Cycles

Systems

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Cycles

The word “cycle” is found in many familiar words.

Bicycle

Tricycle

Unicycle

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• Unicycle - uni (one)• Bicycle – bi (two)• Tricycle - tri (three)

• Since the prefix of each word refers to a number, what do you think the word “cycle” refers to in the above words?

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That’s Right!

The word cycle refers to the wheel.

• A unicycle has one wheel

• A bicycle has two wheels

• A tricycle has three wheels

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We use the word cycle to refer to the motion of going around and around.

In Science – events are repeated over and over in a particular sequence or order. Seasons represent a cycle – spring, summer fall, winter . . . Can you tell where it begins and where it ends?

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Where does a cycle end?That’s right!

It doesn’t.Cycles are continuous.

• The motion we observe on a bike represents the motion in several important cycles in our universe. These cycles never end.

• Here are some of our most important cycles.

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Important Cycles• Water Cycle

• Carbon Dioxide - Oxygen Cycle

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Water Cycle

Evaporation

Condensation

Precipitation

Collection or accumulation

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Water Cycle• Evaporation – liquid changes into a gas

(water vapor)• Condensation – the water vapor cools and

turns back into a liquid (water droplets)• Precipitation – as the droplets increase in

size, gravity causes them to fall back to the earth

Does this cycle ever end?

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Carbon Dioxide - Oxygen CyclePlants on land and in water release oxygen, which we and other animals breathe in. We and other animals breathe out carbon dioxide, which is used by plants in the process of photosynthesis.

Will this cycle ever end?

oxygen

oxygen

Carbondioxide

oxygen

Carbon dioxide

Carbondioxide

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Processes are taking place!• Within each of these cycles, processes

are taking place. • Processes in a cycle are like the verbs in a

sentence. They denote ACTION.• For example, in the water cycle the

processes (actions) taking place are evaporation, condensation, precipitation and collection/accumulation.

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Processes are Actions• Evaporation: liquid changes into a gas.• Condensation: gas (water vapor) changes

into a liquid.• Precipitation: rain, snow, sleet or hail falls

to earth due to gravity. Fog forms.

• Notice how processes involve ACTION words (verbs).

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Find the Processes• What do you think are the ACTION words

in the Carbon Dioxide - Oxygen Cycle?

• Plants on land and in water release oxygen, which we and other animals breathe in. We and other animals breathe out carbon-dioxide, which is used by plants in the process of photosynthesis

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Did you find the action words?

Release oxygen

Breathe In

Photosynthesize

Breathe Out

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Now you know . . . .that cycles have processes

• New Information: Cycles also have STRUCTURES

• Structures in a cycle are like the nouns (OBJECTS) in a sentence. The objects are arranged in a particular way so that they “work” correctly.

• For example, look at the structures in the Water Cycle.

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What are the structures you see?

Evaporation

Condensation

Precipitation

Collection or accumulation

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Structures (Objects) in theWater Cycle

• Water• Ocean, lakes, rivers• Water vapor• Sun• Clouds• Water droplets (rain)

Notice how structures are noun words or objects.

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Find the structures in theCarbon Dioxide - Oxygen Cycle

Plants on land and in water release oxygen, which we and other animals breathe in. We and other animals breathe out carbon dioxide which is

used by plants in the process of photosynthesis.

Carbondioxide

oxygen

oxygen

Carbondioxide

oxygen

Carbon dioxide

Remember to name the objects you see

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Structures (Objects) in theCarbon Dioxide - Oxygen Cycle

• Plants• Bird (animal)• People• Underwater Plants• Fish (marine

animals)

Notice how structures are noun words or objects.

The STRUCTURE of an object is the way the object is designed or arranged so that it does the job it is meant to do. For instance, people have lungs that take in the oxygen. The lungs are arranged especially to breathe in and out.

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REVIEW

• There are many cycles in our world.• Can you name two very important cycles?

Water Cycle

Carbon Dioxide - Oxygen Cycle

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How would you define processes in a cycle?

Processes are the ACTIONS taking placeHow would you define structures in a cycle?

Structures are the OBJECTS in a cycle. They are designed or arranged in a way that allows them to do the work they do.

All Cycles have processes and

structures, which interact.

StructuresProcesses

Structures Processes

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What can be bigger than a Cycle?

A System

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A System is made up of

• Cycles

Cycles, processes, and structures are connected to other cycles, structures, and processes to make up an entire system.

One of the biggest systemsfifth graders learn about is our

Solar System

• Processes • Structures

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Some of the Processes of our Solar System include:

• Revolution of the planets around the sun• Rotation of earth• Revolution of the moon around earth• Movement of comets, asteroids and meteors in

spaceSome of the structures in our Solar System

include:• Sun• Nine Planets (Mercury, Venus, Earth, Mars,

Jupiter, Saturn, Uranus, Neptune, Pluto)• Asteroids• Meteors• Comets

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On a separate sheet of paper, try to draw the Solar System

with the structures listed. How might you show the processes

taking place?

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Other important systems on Earth

• Ecosystems include cycles, processes, and structures that interact in order for the survival of species.

• The two cycles (water and carbon dioxide - oxygen) are all parts of an ecosystem.

• Sometimes we define different ecosystems, such as a desert ecosystem or a rainforest ecosystem.

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Can you identify the cycles, processes and structures in this

desert ecosystem?

Do you think that all of the cycles, processes and structures for a desert ecosystem are drawn in this diagram? Why or why not?

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Two examples of smaller systems are simple and parallel circuits

• A system can be as large as the Solar System or as simple as a circuit.

• The simple circuit above has cycles (energy flow), processes (transfer of energy) and structures (battery, wiring, light bulb, switch).

• The parallel circuit below also has cycles, processes, and structures.

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What about systems in our body?

• Many systems are located in your very own body!

• Can you name some systems?

Digestive System

Respiratory System

These are only two . . . But there are many more!

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• Systems can involve organisms such as an ecosystem or a system in our bodies. (Life Science)

• Systems can involve earth and space objects such as the Solar System. (Earth Science)

• Systems can also involve machines. (Physical Science)

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The most important fact to remember about SYSTEMS is:

• Systems are made up of

cyclesprocesses

and structures

that interact in order for the system to work.

Discuss with your teacher and classmates what you think would happen if one of the parts of a system were removed. Example: What would happen if the sun were removed from the water cycle?