8th Grade Science STAAR Study Sheet—See picture pages for more help.
All of the underlined standards will be on the test-Questions from these standards will make up 60 % of the test.
Organisms and Environments
8.11A Describe producer/consumer, predator/prey, and parasite/host relationships as they occur in food webs within Marine, freshwater, and terrestrial ecosystems.
PrimarySecondaryTertiaryQuaternary
Producer consumer consumer consumer Consumer
AutotrophHeterotrophHeterotrophHeterotroph Heterotroph
HerbivoreCarnivoreCarnivore Carnivore
Omnivores are heterotrophs that are both herbivores and carnivores
Symbiotic relationships: mutualism or + +, commensalism or + 0, parasitism :( or + -predator/prey is a form of parasitism, one is harmed.
8.11B Investigate how organisms and populations in an ecosystem depend on and may compete for biotic and abiotic factors such as quantity of light, water, range of temperature, or soil composition
There will be only so much open areas of light, water, shelter, and a helpful temperature, as well as food in an ecosystem to support the organisms living there. They will compete for those resources to survive. Not having enough of just one of these resources can limit the populations of organisms in the ecosystem.
8.11C Explore how short-and long-term environmental changes affect organisms and traits in subsequent populations (the next generations).
Drought, flood, heat wave, or fire would be short-term environmental changes. Volcanic eruptions, climate change, and the introduction of invasive species (organisms that didn’t naturally live there) are long-term environmental changes. Humans can cause both short and long term changes to an environment.
Organisms with traits already in their DNA that can help them survive changes to the environment will reproduce and pass those helpful traits to their offspring. The next generations will have more good traits. That changes the specie’s genetics. Organisms without the good traits die and don’t reproduce.
Matter and Energy
8.5A Describe the structure of atoms, including the masses, electrical charges, and locations of protons and neutrons in the nucleus, and electrons in the electron cloud.
Protons have a + charge, Neutrons have a neutral charge 0 and are in the nucleus. Electrons have a – charge and are in the electron cloud. Protons + Neutrons = Atomic Mass. Atomic mass – protons = neutrons. Protons and Neutrons have the same mass. Electrons have almost no mass.
8.5B Identify that the protons determine an element’s identity and valence electrons determine its chemical properties, including reactivity.
The atomic number is the number of protons in the nucleus. That determines if an element is Hydrogen, Lithium, Nitrogen, Oxygen, etc. The periodic table is arranged by increasing atomic number. As 1 more proton is added in the nucleus, you move to the next element on the periodic table.
Electrons should be in the same number as protons. The positive and negative charges are equal in number and cancel each other out. That makes a neutral atom.
8.5C Interpret the arrangement of the Periodic Table, including groups and periods, to explain how properties are used to classify elements.
Electrons can be in energy levels by the following rule: 2 maximum in energy level 1, after that 8 electrons is the final number.
If an atom has only 1 energy level, and there are 2 electrons in it, it has 2 valence electrons and is stable and will not react. If levels 2-7 are the valence level and they have 8 electrons, they are stable and will not react. The Noble Gasses do not react with other elements. They are in the last column or “group.”
Reactivity
Valence electrons are the electrons in the outer energy level of any atom. If the element is a metal, it will lose electrons (react) in the valence level to become stable. Non-metals will gain electrons (react) to become stable, and metalloids will have some characteristics of metals and non-metals. You must know which elements are metals, metalloids, and non-metals, and noble gasses, and which groups are most reactive. Nobles gasses in the last column do not react (least reactive).
6.6A (metals are shiny and conduct electricity and heat and are malleable and ductile-bend and stretch)
(Non-metals are dull, don’t conduct electricity and heat and are brittle(break easily)— good insulators
Columns: Group numbers are the numbers at the top of the columns on the periodic table and represent the number of valence electrons an element has. This determines how they will react (lose or gain electrons). All the elements in the same group (column) have the same number of valence electrons and have the same reactivity or “properties.”
Rows: Rows are called periods and represent the energy levels each atom has.
8.5D Recognize that chemical formulas are used to identify substances and determine the number of atoms of each element in chemical formulas containing subscripts.
Compounds have more than one element. Numbers called subscripts (written below the line) tell us how many of each atom are in a compound. H2O—two atoms of hydrogen and 1 atom of Oxygen
8.5F recognize whether chemical equations containing coefficients are balanced or not and how that relates to the law of conservations of mass-what you start with you must also have in the end
C6H12O6 +6 O2 6CO2 + 6H2O is a balanced equation for respiration
8.5E investigate how evidence of chemical reactions indicate that new substances with different properties are formed.
Evidence of chemical reactions: gasses produced, precipitate forms, color changes, pH changes, temperature change (heat given off or heat taken in (feels cold)
Physical change: solid to liquid to gas to liquid to solid. Breaking into smaller pieces. Dissolving in water.
Force, Motion, and Energy
8.6A Demonstrate and calculate how unbalanced forces change the speed or direction of an object’s motion.
Force is measured in newtons (N). You will be given a model, or picture, or a story about how many N of force are applied in one or more directions. If all forces are in the same direction, add them together. If they are in different directions, subtract them. The direction with the larger force is the direction the object will move in, but only with the N’s that are left after you subtract them.
8.6B Differentiate between speed, velocity and acceleration. This is vocabulary, but you will need to use equations in some problems on the test.
Speed- distance divided by time.
Velocity-distance divided by time, but in a specific direction (north, south, east, west, up, down, etc.)
Acceleration—this is how speed or velocity change while an object is moving. It could be going faster or slower than when it started. (Unbalanced forces cause acceleration, not just movement)
If N (newtons) are constantly applied to a moving object, it will accelerate, or go faster, because force is
being applied the whole time! To calculate acceleration you must subtract the initial (beginning) speed or velocity from the final (last) speed or velocity and then divide by time.
8.6C Investigate and describe applications of Newton’s law of inertia, law of force and acceleration, and law of action-reaction such as in vehicle restraints, sports activities, amusement park rides, Earth tectonic activities and rocket launches.
Inertia—an object in motion will stay in motion or an object will stay at rest unless a force acts on it.
In cars, we wear seat and shoulder belts to hold us in the seat. In sudden stops, the car stops but objects in the car keep moving.
In baseball, the ball moves in one direction when pitched, but when the force of the bat hits it, it changes direction and moves until it is caught or gravity slows it down.
Force and acceleration—F=m x a. or m = F divided by a, or a = F divided by m. Use the triangle!
Equal and Opposite action—Any action (force) in one direction is equaled by an equal reaction (force) in the opposite direction.
When dribbling the ball in basketball, the ball hits the floor with a certain amount of force. The floor reacts to the ball with the same amount of force and the ball moves back up.
I F E O. Say Ifeo several times and remember to write it on your formula chart to help you remember Newton’s Laws of motion and which one is first, second, and third.
First Law: Inertia
Second Law: Force and acceleration
Third Law: Equal and Opposite—action/reaction
Earth and Space
Believe it or not, this is where many people trip up.
8.7A Model and illustrate how the tilted Earth rotates on its axis, causing day and night, and revolves around the Sun causing changes in seasons.
You will most likely have pictures (models) of the Earth rotating (spinning) and orbiting the Sun (revolving). Because of the 23.5 degree tilt on its axis, sunlight is not evenly distributed on Earth. Some parts are colder and some warmer, because of the tilt. Summer in the northern hemisphere is winter in the southern hemisphere. Solstice, and equinox are vocabulary terms to remember.
8.7B Demonstrate and predict the sequence of events in the lunar cycle. You have had a lot of practice!
Mark your formula chart with : New, 1, Full, 3. This reminds you the order or sequence of phases. New, first quarter, full, third quarter. There are 7 days between these main phases. The phases between those main phases are waxing crescent and gibbous and then waning gibbous and crescent. Back to new moon.
Waxing means the light is growing larger, and waning means the light is growing smaller.
8.7C Relate the position of the Moon and Sun to their effect on ocean tides.
This is about gravity. The moon and sun are close enough to Earth to pull the oceans away from the surface of Earth. This makes them bulge out on two sides of the Earth, which means the water is squeezed thinner on the other sides. That makes high and low tides. Because the Earth is turning, the part of the ocean in the bulge is constantly changing—the tides go in and out!
Gravity—The larger the object, the more gravity it has. The moon is close to Earth so it has a big effect. The sun is farther away, but is enormous, so it also has an effect on our oceans.
Many people missed this question last year.
8.8A Describe components of the universe, including stars, nebulae, and galaxies, and use models such as the Hertzsprung-Russell diagram for classification.
You must know how to read the labels on the Hertzsprung-Russell Graph. Hotter is to the left, and brighter is near the top. Super Giants are very bright so they are near the top, but they are only bright because they are so BIG. They are actually cool as stars go, so they are to the right side. White dwarfs are very hot, so they are on the left, but because they are so small, they do not appear very bright. They are near the bottom. It is easy to read if you take the time to be careful.
There are three types of galaxies: spiral, elliptical (oval), and irregular. Nebulae are gas clouds that are the birth-place of stars. Comets are dirty ice balls that have eccentric orbits that take them very far away from the Sun and then very close to the Sun. Asteroids can be large and small and are pieces of material left over from the formation of the solar system.
8.8C Explore how different wavelengths of the electromagnetic spectrum such as light and radio waves are used to gain information about distances and properties of components in the universe.
Red Shift!—We know the universe is expanding because of the light from stars and galaxies shifting to the red side of the spectrum. This supports the Big Bang Theory—Everything in space is moving outward from a central starting point.
8.8D Model and describe how light years are used to measure distances and sizes in the universe.
Light years measure distance!!! Light takes a specific amount of time to travel a specific distance in a year. You are looking back in time when you look at the stars!It took a long time for the light to reach us.
8.9B Relate plate tectonics to the formation of crustal features.
This means that the force of the movement of the plates creates features on Earth’s crust.
Trenches form where one plate subducts under another. They always form on oceanic plates. Volcanoes form above a subducting plate—ocean plate or continental plate. Folded mountains like the Himalayas form when two continents collide. Rift Valleys form when plates pull apart, and Faults form as the plates move, especially where they slide past one another. Earthquakes occur along faults, big and small.
Boundaries: convergent, divergent, transform.
8.9A Describe the historical development of evidence that supports plate tectonic theory.
Wegener noticed fossils of a fern (glossopteris) and animals on separate continents. He noticed that fossils of plants and animals that need warm climates can be found in places that are cold today. Mountain ranges on separate continents have similar rock layers and folds—they were once together.
8.9C Interpret topographic maps and satellite views to identify land and erosional features, and predict how these features might be reshaped by weathering.Know terms like Delta, gully, valley, canyon, watershed, and be able to recognize them in topographic maps. Also be able to say how the land might change with more weathering and erosion. Wind does a lot, but water does the most weathering and erosion.
40% of the questions will be from the following standards. A few of these standards will not be on the test, but most of them will be. They are often included in questions from the standards that are certain to be on the test!
Organisms & Environment--Write on your formula chart: Pro means No Eu means Nu
8.11D Recognize human dependence on ocean systems and explain how human activities such as runoff, artificial reefs, or use of resources have modified these systems.
Humans depend on the ocean as a food source. The land cannot provide enough for everyone. The ocean absorbs a lot of carbon dioxide from the atmosphere, and algae use a lot of carbon dioxide for photosynthesis. In fact, most of the oxygen in the atmosphere comes from photosynthesis in the algae in the ocean. (phytoplankton) So . . . we depend on the ocean for food and oxygen! And—to remove CO2 from the air!
Marine (ocean) ecosystems depend on constant water temperature, sunlight, and a balance of chemicals and pH in the water. Humans have increased global warming which changes water temperature, and the chemistry of the water. Fertilizers are rich in nutrients. In the ocean, too many nutrients cause too many phytoplankton to grow. They use more oxygen than they make, and cause other creatures to die because of a lack of oxygen in the water. There go the food webs! (we depend on ocean food webs!)
Remember—All drains go to the ocean, kid! (All watersheds go to the ocean, too, and we have fertilizer running off fields into watersheds.) Oil spills, chemical dumps, removing too many trees . . .
Coral reefs need sunlight to support a food web. But coral are sensitive to water chemistry and temperature changes. Many coral reefs are dying because of human interference. But, humans sink old oil rigs and ships to give new coral a place to attach and grow, to help restore balance to the ocean.
7.10B Describe how biodiversity contributes to the sustainability of an ecosystem
Biodiversity means a great variety of organisms living in an ecosystem. If there are many resources, an ecosystem can support many living things, which support each other. If one thing goes wrong, there are enough other organisms and resources to keep an ecosystem going. Rain forests have high biodiversity, deserts and tundra have low biodiversity—they suffer more problems if something goes wrong.
7.10C Observe, record and describe the role of ecological succession such as in a microhabitat of a garden with weeds.
Succession is the change in plants, animals, fungi, etc. that live in an area over time. Primary succession occurs after an area is returned to bare rock, like a volcanic eruption. Secondary succession may start if soil is still there after a disaster like fire. If a garden is forgotten, natural plants (weeds) will grow from seeds blown by wind, or dropped by animals and begin to take over. Gradually, larger plants will become established and more animals will be able to live there. A climax community is the final stage with hardwood trees. Pioneer species are the plants that can begin on bare rock or soil. Lichen and moss are pioneer species for primary succession. Weeds and grasses are pioneer species for secondary succession.