grade staar science review
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GRADE 8 STAAR SCIENCE
REVIEW
Written by Chris Jackson, Ed.D.www.hedgehoglearning.com
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© Hedgehog Learning
All clipart and images used in this review are either created by Hedgehog Learning, found in public domain, or used with permission from iStockphoto, iClipart, Microsoft, or 123RF
MATTER AND ENERGYTEKS 8.5A (R), 8.5B (R), 7.5C (S), 7.6A (S), 7.6B (S)
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Protons, Neutrons, and Electrons
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Nucleus of the Atom Contains Protons and Neutrons
Electron Cloud of the Atom Contains Electrons
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Protons Neutrons Electrons
Mass of Particle(1, 0)
Charge of Particle(1, 0, +1)
Location of Particle
Take a minute to fill in the table below on a piece of paper…
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Protons Neutrons Electrons
Mass of Particle(1, 0)
1 1 0
Charge of Particle(1, 0, +1)
+1 0 1
Location of Particle Nucleus Nucleus Orbitals or Electron Cloud
Is this what you came up with?
Makeup of an Element
The ATOMIC NUMBER indicates the number of PROTONS in an ELEMENT
The ATOMIC MASS (rounded) indicates the number of PROTONS plus NEUTRONS
Only Oxygen has 8 protons, which makes it a unique element.
To find the number of neutrons, subtract the atomic number from the atomic mass: 16 – 8 = 8
Electrons are normally equal to the number of protons if the charge of the atom is zero.
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Element + Element = Compound
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• Most elements will either gain or lose valence electrons and become charged.
• Nonmetals (right side of periodic table) typically gain electrons and are negatively charged.
• Metals (left side of the periodic table) typically lose electrons and are positively charged
• Because metals and nonmetals are oppositely charged, these individual elements will combine to form compounds.
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12 P 8 P
Mg O
= VALENCE ELECTRON
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12 P 8 P
= VALENCE ELECTRON
Mg O
Lose 2 Electrons+2 Charge
Gain 2 Electrons2 Charge
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• The number of valence electrons will determine how reactive an element will be.
• If an element has valence electrons to gain or lose, it will be very reactive.
• If an element has all eight valence electrons, it is considered to be nonreactive.
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Identify examples of physical and chemical changes that occur at each of these points.
A
B
C
Energy and Food Webs
On a piece of paper, diagram the flow of energy through these organisms.
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Organic Compounds
Organic Compoundsare compounds containing carbon.
Organic compounds are the building blocks of life, including substances like fats, sugars, and protein.
Fossil fuels are also organic compounds.
Can you identify any other carboncontaining compounds?
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CARBON
Hydrogen
Oxygen
SulfurNitrogen
Phosphorus
MATTER AND ENERGYTEKS 8.5C (R), 8.5D (R), 6.5C (S), 6.6A (S), 6.6B (S)
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PE
RIO
DS
GROUPS
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METALS
Alkali and Alkaline Metals
Transition Metals
• Conducts heat• Conducts electricity• Solid• Lustrous• Malleable
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METALLOIDS
• Semiconductors of electricity
• Properties of metals and nonmetals
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NONMETALS
• Gas or Liquid• Poor conductors of
electricity and heat• Reactive with
metals• Noble gases (green
column) are unreactive.
Elements and Compounds
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2AB + C2 � 2CB + 2A
Reactants Products
Coefficient Subscript Compound Element
MATTER AND ENERGYTEKS 8.5E (R), 8.5F (S)
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a change when a new substance is formed from the
reaction between two or more different substances
CHEMICAL CHANGE
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a change in the temperature, state of matter, shape, density,
or any other observable characteristic of a substance
PHYSICAL CHANGE
Mass of Reactants = Mass of Products
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Before
After
How does the mass of the egg change before and after cooking? Do the physical and chemical changes affect the mass?
Law of Conservation of Mass in Chemical Reactions
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H2 + O2 � H2O
On a piece of paper, balance this reaction between hydrogen and oxygen gas.
Law of Conservation of Mass in Chemical Reactions
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2H2 + O2 � 2H2O
4 atoms of Hydrogen on both sides
2 atoms of Oxygen on both sides
Was this your answer?
FORCE, MOTION, AND ENERGYTEKS 8.6A (R), 8.6B (S), 6.8C (S), 6.7D (S)
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Forces
Consider the forces acting on these books.
Are the books moving?
Are the forces balanced or unbalanced?
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Gravity pulling downward
Table pushing upward
Air pressure
Air pressure
Forces
Balanced Forces occurs when multiple forces acting on an objects does not cause an object to change its speed
Unbalanced Forces occurs when multiple forces acting on an object causes the object to increase or decrease speed
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Identify if these items are examples of BALANCED or UNBALANCED forces.
Constant speed
What is the net force acting on these objects? Will these objects change speed?
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15 N
25 N3 N 1 N
2 N
2 N
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• Speed – the distance an object travels in a certain amount of time• Velocity – the speed and direction of an object• Acceleration – a change in velocity
An airplane flies from Dallas to Boston, a distance of 1500 miles, in 4 hours. Describe the flight of the
airplane in terms of average speed and velocity. When does the airplane accelerate?
FORCE, MOTION, AND ENERGYTEKS 8.6C (R), 7.7A (S), 6.8A (S), 6.9C (S)
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#3 – every action has an equal and opposite reaction
#1 – an object will only change speed if acted on by an unbalanced force Law of Inertia
#2 – the acceleration of an object is related to the its mass and the force acting on it
F=ma
Identify which law of motion is being represented.
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• A moving red billiard ball hits the side bumper on the table and bounces backward at nearly the same speed.
• An airbag inflates to help cushion to rapid deceleration of the people inside the car during an accident.
• A powerful rocket engine producing more force is used on a more massive rocket to produce the same acceleration.
Energy
Potential EnergyThe energy that results due to an object’s position
Kinetic EnergyThe energy derived from an object’s motion
When is kinetic energy converted to potential energy during a roller coaster ride?
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Highest Potential Energy
Highest Kinetic Energy
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Work – the energy needed to move an object over a certain distance
The woman had to pick up a box with a mass of 5 kg and lift it a distance of 2 meters.
How much work did she do?
Would the amount of work change if she used a ramp to help her?
2 m
5 kg
Energy Conversions
Name the energy conversions in each of the pictures to the right using the following terms:
Solar EnergyMechanical EnergySound EnergyChemical EnergyElectrical EnergyLight Energy
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EARTH AND SPACETEKS 8.7A (R), 8.7B (R), 8.7C (S), 6.11B (S)
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ROTATION OF THE EARTH
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The Earth rotates once every 24 hours or 1 day.
The rotation of the Earth causes day and night since the side facing the Sun is always moving.
The rotation of the Earth does not cause seasonal changes.
sunlightDAYNIGHT
REVOLUTION OF THE EARTH
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The Earth revolves around the Sun every 365 days or 1 year.
The Earth’s revolution causes the changes in the seasons due to the tilt of the Earth.
The revolution of the Earth does not cause day or night.
SUMMER
SUMMERWINTER
WINTER
Phases of the Moon
The Moon revolves around the Earth about once every month.
What phase of the Moon will occur about two weeks after a full moon?
What phase of the Moon will occur about one week after the first quarter?
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Mass = Gravity
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Gravity is the force that holds the solar system together.
The mass (and thus gravity) of the Sun keeps all the planets orbiting around it.
The mass (and thus gravity) of the Earth keeps the Moon orbiting around it.
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The Moon has much greater affect on the Earth’s tides because it is closer to the Earth.
When the Moon, Sun, and Earth are aligned (new and full Moon), the tides are the greatest (Spring Tide)
EARTH AND SPACETEKS 8.8A (R), 8.8B (S), 8.8C (S), 8.8D (S)
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1 second Moon
8 minutes Sun
1 hour Saturn
4.2 years Nearest Star (Proxima Centauri)
6,500 years Crab Nebulae
26,000 years Center of the Milky Way
2,500,000 years Nearest galaxy (Andromeda)
93,000,000,000 years Other side of the universe
If we were traveling at the speed of light, it would take us _________ to reach ________.
Our own personal star
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Our solar system is extremely tiny compared to the Milky Way Galaxy.
Stars
The stars we see at night are located “nearby” in the Milky Way galaxy.
Stars in other galaxies are too far away for us to see them individually.
Stars have “life cycles” similar to plants and animals. Average stars, like our Sun, are born in nebulas and die as red giants.
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Models, like a HertzsprungRussell diagram, show us how stars change over time.
Based on this diagram, what would you say about the age of our Sun compared to other stars on the main sequence?
Hotter Cooler
Bri
gh
ter
Galaxies
Our galaxy, the Milky Way galaxy, is made up of BILLIONS of stars.
There are BILLIONS of galaxies in the universe.
Types of galaxies include:• Spiral galaxies• Barred spiral galaxies• Elliptical galaxies• Dwarf galaxies• Ring galaxies
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EARTH AND SPACETEKS 8.9B (R), 8.9C (R), 8.9A (S), 8.10A (S), 8.10B (S), 8.10C (S), 7.8C (S)
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Which of these two landscapes is hundreds of miles away from a crustal boundary?
Give a reason to support you answer.
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1 23
At which number on the map are the following crustal features occurring?
A. Tall mountain range formed from one plate moving into another plate.
B. A midocean ridge where two plates are separating.
C. Earthquakes where two plates are moving past each other.
Constant reshaping of our planet
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What features can you identify in this satellite picture?
What are the brown areas?
Where does this come from?
Where is it going?
Identify these weather symbols and describe what they mean.
In which direction to high pressure systems rotate in Texas? Where is the world would they rotate the other direction?
What is responsible for all moving currents, both in the atmosphere and in the ocean?H L
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Hurricanes occur in the Atlantic ocean during the summer and fall. Why do they occur during this time and not during the winter?
Where does the energy for hurricanes come from?
In which direction to hurricanes rotate in the Northern Hemisphere? Southern Hemisphere?
ORGANISMS AND ENVIRONMENTSTEKS 8.11A (R), 8.11B (R), 7.10B (S), 7.10C (S), 7.11C (S), 8.11D (S)
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In the food web to the left, what role does the Sun play?
Identify the producers, consumers, and decomposers.
How does the ant play a part in the food web?
What would happen to the snake population if the rabbits were overhunted?
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Parasites
A parasite is an organism that must get its energy from another organism.
Sometimes the relationship is mutually beneficial.
Sometimes one organisms causes the other harm.
Can you think of a parasite that benefits it host?
What about the mosquito in the picture?
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Look at the ecosystemin the picture to the left.
Suppose a fire disturbed this area 10 years ago. How has ecological succession occurred since then.
How is competition for resources occurring in this ecosystem?
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Ecosystem
In this ocean ecosystem, how are organisms are competing for:
• Sunlight• Living space• Food• Oxygen
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How does natural selection explain why giraffe’s have long necks?Why is biodiversity important to natural selection?
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ORGANISMS AND ENVIRONMENTSTEKS 8.11C (R), 7.11A (S), 7.12B (S), 7.12D (S), 7.12F (S), 7.14B (S), 7.14C (S), 6.12D (S)
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Why did the environmental changes in the early 1900’s in England cause the “gray” peppered moth to decline, but the “black” peppered moth increased in population?
Genetic trait for skin tone and skin cancer risk
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People with a genetic trait for fair skin are more likely to get skin cancer during their lifetime.
Fairerskin humans generally originated further away from the equator than darkerskin humans.
Explain how the environment influenced early human traits for skin tone.
Dichotomous Keys
Dichotomous keys help us to identify organisms based on their physical characteristics.
What is the dichotomous key in the picture used to identify?
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Reproduction
Sexual ReproductionRequires male and femaleFewer offspringGreater genetic variation
Asexual ReproductionRequires only one parentMany offspringLess genetic variation
What are the advantages of sexual reproduction in fighting off certain illnesses over multiple generations?
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Some plants can reproduce asexually.
Animals reproduce sexually and produce fewer offspring.
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Parts of a CellLooking at the diagram on the right:
1. Where is the genetic material contained?
2. Is this cell prokaryotic or eukaryotic?
3. Is this cell autotrophic or heterotrophic?
4. Would this cell be found in the animal kingdom?
Building artificial reefs to replace those damaged by humans
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Many coral reefs have been damaged or destroyed by human activity and pollution.
In an effort to restore destroyed reefs, scientists have created artificial reefs like the one in the picture.
What other ways have humans influenced the ocean habitat?
Best wishes for success on the Grade 8 Science STAAR!
Written by Chris Jackson, Ed.D.www.hedgehoglearning.com
© Hedgehog Learning
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