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GRADE EIGHT (2005 Standard 8-2) Science Topic EARTH’S BIOLOGICAL HISTORY KEY CONCEPTS & TERMS (** for teacher/parent reference - not a student assignment) KEY TERM: Populations DEFINITION: Variations organisms in a particular environment that are adapted to living conditions there – are more likely to survive there a group of organisms that have similar characteristics to each other and that typically reproduce only with each other differences within species based on traits Adaptation a trait or behavior that helps an organism to survive and reproduce Natural selection the natural process by which some organisms survive and reproduce because they have traits favorable to survival in an environment, while others die out because they lack those traits the preserved remains or traces of a once-living organism, usually more than 10,000 years ago a cavity in a rock that has the shape of the organism that was trapped there a type of fossil formed when an earlier fossil in rock is dissolved away, leaving behind the impression of that fossil, and new sediment or minerals enter the mold plant or animal remains that have been petrified or “turned to rock” when minerals soak in, replace the remains, and harden a fossil that forms when the organisms or parts of organisms are prevented from decaying by being trapped in ice, tar, or amber a fossil impression in a rock, consisting only of a thin carbon deposit / imprint in the rock fossilized tracks and other evidence of animal activity Species Fossil Mold fossil Cast fossil Petrified remains Preserved fossil Carbonized fossil Trace fossils Geologic time scale Precambrian the division of Earth’s history into smaller units based on the types of life-forms living during certain periods the oldest and longest span of geologic time Mesozoic Era the time periods in the Earth’s history after Precambrian separated by disturbances in the Earth’s crust and changes in living things the oldest era – immediately after Precambrian; organisms developed hard parts the middle era of Earth’s geological history; reptiles were dominant Cenozoic Era the era of present day Earth; diversity of life forms increased Periods Cambrian period the subdivision of eras based on life existing at the time and on geologic events the first period of geologic time Quaternary period the present period of geologic time Eras Paleozoic Era Epochs the subdivision of periods during the Cenozoic era Holocene epoch the present epoch of geologic time Relative age no specific age in years is implied – a comparison of older and younger Law of Superposition a scientific law stating that, in layers of undisturbed rock, the oldest are on the bottom and rocks become younger toward the top rock layers Strata Index fossils Trilobite Extinct / Extinction fossils formed from species that existed on Earth for short periods of time, were abundant, and were widespread geographically an example of an index fossil; a hard-shelled animal whose body had three sections when a species has no members that are still alive; the population of that species no longer exists GRADE EIGHT (2005 Standard 8-3) Science Topic EARTHS STRUCTURE & PROCESSES KEY CONCEPTS & TERMS (** for teacher/parent reference - not a student assignment) KEY TERM: DEFINITION: Crust the Earth’s uppermost / outermost layer Lithosphere large sections of Earth’s crust and upper mantle Mantle the largest, thickest layer inside the Earth, below the crust Asthenosphere Outer core the plastic-like layer of the Earth below the lithosphere; the top of the mantle the liquid layer surrounding the inner core, below the mantle Inner core the solid center layer of Earth Density a physical property of a substance that compares the mass of the material present to the volume that material occupies – the more mass within a volume of space, the greater the density a sudden movement of Earth’s crust usually along cracks in the crust known as faults energy waves, caused by an earthquake, that spread out in all directions from the epicenter; one type causes the movement of crust material when it reaches the surface longitudinal waves that move out from the earthquake focus pushing and pulling rock creating a back and forth motion in the direction of the wave transverse waves that move out from the earthquake focus moving at right angles to primary waves causing rocks to move up and down and side to side waves that form when P and S waves reach the surface; can cause ground to shake making rocks sway and roll like an ocean wave materials in Earth’s core are inferred to produce lines of magnetic force around Earth; a compass needle will align with that field an instrument used to detect and measure seismic waves Earthquake Seismic waves Primary (P) waves Secondary (S) waves Surface waves Earth’s magnetic field Seismograph Seismogram Epicenter the vibration record that looks like jagged lines on paper where the seismograph needle moves along with the incoming earthquake waves the point on Earth’s surface directly above the origin of an earthquake Focus the point where earthquake energy is released Triangulation Igneous rocks by using the records from three seismograph stations, the location of an earthquake epicenter can be plotted rock formed by the cooling and hardening of molten material Intrusive igneous rocks rocks formed below Earth’s surface from magma cooling slowly Extrusive igneous rocks rock formed on the Earth’s surface from lava that cools rapidly Metamorphic rocks rocks formed from changing existing rocks due to heat and pressure Sedimentary rocks rocks formed from the compaction or cementation of sediments Chemical sedimentary rocks Rock cycle rocks formed from minerals precipitated from a solution or left behind by evaporation the ongoing processes that form and change rock from one kind to another natural, solid materials found on Earth that are the building blocks of rock; different minerals have different physical and chemical properties that determine their use and value minerals that are mined because they contain useful metals or nonmetals Minerals Ores Fossil Fuels Plate tectonics Convection current Divergent plate boundary Convergent plate boundary Subduction zone Transform plate boundary Pangaea Volcano Volcanic eruptions natural fuels that come from the remains of living things; they give off energy when they are burned the theory that Earth’s crust and upper mantle exist in sections that move called lithospheric plates the heating, rising, cooling, and sinking of matter; the movement of material is caused by uneven heating boundary between plates that are moving apart boundary between plates that are colliding the area where one lithospheric plate slides under another at convergent plate boundaries; some crust is destroyed boundary between plates that are sliding past each other at one time in geologic history the continents were joined together in one large landmass called by this name a mountain built of cooled lava, volcanic ash, cinders, and rock Magma are constructive Earth processes in that they add new rock to existing land; explosive eruptions can also be destructive liquid rock from the mantle that rises to Earth’s surface Lava liquid rock, magma, that flows out onto Earth’s surface Vent the opening in a volcano where magma flows out Tension forces that pull rocks apart Shearing forces that push on rocks from either side of faults causing them to push Compression a force that pushes on rocks from opposite directions Normal fault a break in the rock caused by tension forces Reverse fault a break in the rock caused by compression forces Thrust fault a break in the rock caused by shearing forces Fault-block mountain forms if normal faults uplift a section of rock Aerial photography / imagery high-flying aircraft or satellites use sensors and cameras to gather the information about Earth’s landforms and resources; computers create images from the data a map that uses contour lines and intervals to show the varying elevations of Earth’s surface; provides information on elevation, relief, slope of the ground surface Topographic map GRADE EIGHT (2005 Standard 8-4) Science Topic ASTRONOMY: Earth & Space Systems KEY CONCEPTS & TERMS (** for teacher/parent reference - not a student assignment) KEY TERM: Solar System Asteroid Comet Meteoroid Photosphere Corona Sunspots Prominence Solar flare Solar winds Aurora Rotation Revolution Elliptical Phases of the Moon DEFINITION: objects that orbit the central star, known as the Sun; e.g. planets, moons, asteroids, comets, meteoroids a piece of rock, smaller than a planet, that orbits the Sun; many are found orbiting in a region between Mars and Jupiter a mass of frozen gases and rock particles that orbits the Sun a chunk of rock that moves about within the solar system; called a meteor if it enters a planet’s atmosphere; called a meteorite if it impacts the surface of a planet or moon most prominent layer of the Sun’s atmosphere; emits the light we see; is blocked during a total eclipse the outermost and largest of the layers of the Sun’s atmosphere dark areas of the Sun’s surface, which are cooler than surrounding areas a mass of glowing gas looping out from the surface of the Sun, usually near sunspots a sudden burst of hot gas from the Sun that releases large amounts of energy into space a stream of electrically charged particles flowing from the Sun illumination of the sky near the poles as a result of solar particles entering the ionosphere spinning on an axis; a day on Earth is based on a 24 hour rotation the circling of one object around another object; a year on Earth is based on 365 ¼ days for revolving around the Sun the slightly oval shape of Earth’s orbit around the Sun Waxing phases the appearance of the Moon that depends on how much of the sunlit side of the Moon faces Earth the lighted side of the Moon gradually increases Waning phases the lighted side of the Moon gradually decreases New moon none of the lighted side of the Moon faces the Earth Crescent moon a small slice of the lighted side of the Moon is facing Earth Quarter moon one-half of the lighted side of the Moon faces Earth Gibbous moon more than one-half of the lighted side of the Moon faces Earth but not yet full all of the lighted side faces the Earth Full moon Eclipse Tides Spring tides Neap tides Tilt of Earth’s axis Seasons Solstice Equinox Gravity/ gravitational attraction Mass Weight Spring scale Galaxy Milky Way Galaxy Light year Optical telescope Radio telescope Satellite (man-made) Space probe Spectroscope the shadow caused by a body blocking the light from another Solar eclipse – when the Moon is directly between the Sun and Earth, blocking the Sun’s light casting a shadow over a certain area on Earth Lunar eclipse – when Earth is directly between the Sun and the Moon, blocking the Sun’s light so that Earth’s shadow is cast over the Moon daily changes in the level of the surface levels of Earth’s oceans due to the gravitational pull of the Moon and the Sun higher than usual high tides and lower than usual low tides caused by the lining up of the Sun, Moon, and Earth; occur when the gravitational pull of the Sun and Moon are combined tides that are not as high or low as usual caused by the Sun and Moon being at right angles to the Earth; occur when the pull of the Sun and Moon act against each other the central line around which the Earth spins is not straight up-and-down but is slanted at a 23 ½ degree tilt periods of time in Earth’s year that have different numbers of hours of daylight and different angles to the Sun’s rays because of Earth’s tilted axis either of two days during the year when the tilt of Earth causes the length of day to be the longest or the shortest either of two days during the year when the Sun is directly above the equator; daylight and night are the same length the force of attraction between two masses; a more massive object has greater pull on a less massive object; the closer the objects, the greater the pull the amount of matter in an object; is the same no matter where the object is located the measure of gravitational force on an object; influenced by mass but they are not the same tool used to measure weight are regions in outer space made up of billions of stars, gas, and dust clouds; they have different shapes – elliptical, spiral, irregular the name given to the spiral galaxy of which the Sun and its solar system are a part a unit of distance that astronomers use to measure distance to stars and galaxies in space; equal to the distance light travels in one year a tool used to collect visible light, then uses lenses or mirrors to focus the light producing larger, brighter images; may be reflecting or refracting an instrument that uses a large antenna to gather radio waves emitted from objects (stars and galaxies) in space an object place in orbit that contains instruments and/or telescopes to collect information from space contains instruments and travels through space to gather information and transmit it back to Earth an optical instrument that separates the light given off by an object into bands of different colors; can be used to identify elements in a star GRADE EIGHT (2005 Standard 8-5) Science Topic FORCES & MOTION KEY CONCEPTS & TERMS (** for teacher/parent reference - not a student assignment) KEY TERM: Motion Position Reference point Direction Speed Average speed Time-distance graph Force Gravitational force / gravity Friction DEFINITION: occurs when there is a change in position compared to a fixed object at a reference point the actual location of an object the position of a stationary object that allows for measurement of distance of a moving object the line or path along which something is moving, pointing, or aiming; the relationship of the position of a moving object to another position the rate of change of the position of an object; the amount of distance covered in a given period of time; can be calculated using the formula: v = d / t the total distance traveled divided by total time of travel A representation of how both speed and distance change with time; the slope of the graph can be used to describe the speed of an object a push or pull Balanced forces a force that always attracts without direct contact; an attraction between any two objects that have mass a force between surfaces that are touching that opposes motion of an object or surface past another forces that are equal in strength and opposite in direction Unbalanced force a force that is not opposed equally by another force on the same object Vectors (force arrows) directional symbols used to express the magnitude and direction of balanced and unbalanced forces the strength of a force; is represented by the length of the arrow in a vector arrow the tendency of an object to remain at rest or to keep moving in a straight line until a force acts on it Magnitude Inertia GRADE EIGHT (2005 Standard 8-6) Science Topic WAVES KEY CONCEPTS & TERMS (** for teacher/parent reference - not a student assignment) KEY TERM: Wave Medium DEFINITION: a repeating disturbance, vibration, or movement that transmits (transfers or moves) energy from place to place a material through which waves can travel Crest waves that travel through matter – require a medium to vibrate in order for energy to be transferred; e.g. sound waves, water waves waves that do not require a medium to exist – can travel through matter or empty space where matter is not present; e.g. light, radio waves mechanical waves in which the particles of matter in the medium vibrate by pushing together (compression) and moving apart (rarefaction); e.g. sound waves, some seismic waves mechanical waves in which the particles of matter in the medium vibrate by moving back and forth at right angles to the direction the waves travel; e.g. waves on a rope, strings on a musical instrument, some seismic waves, electromagnetic waves the highest point of a transverse wave Trough the lowest point of a transverse wave Wavelength a property of a wave that is the distance between one point on a wave and the nearest point just like it on the very next wave a property of a wave that is a measure of the number of full wavelengths that pass a point in a certain amount of time a property of a wave that is a measure of the greatest distance that vibrations in a wave move from their normal position as the wave passes a property of a wave that is a measure of the distance per time that a given wave travels; a particular type of wave has a wave speed that is constant in a specific medium or in space a wave behavior that is the bending of waves due to a change in speed as the wave moves from one medium to another a lens whose middle part is thicker than its edges so that it bends/refracts light rays together a triangular-shaped piece of glass that refracts/separates light into its various frequencies / colors A material with many slits or tiny ridges that refracts light at different angles into its various frequencies / colors a wave behavior that is the bouncing back of waves upon reaching another surface or boundary that does not absorb the wave’s energy a mirror with a smooth, flat surface that that reflects light Mechanical waves Electromagnetic waves Compressional / Longitudinal waves Transverse waves Frequency Amplitude Wave speed Refraction Convex lens Prism Diffraction gratings Reflection Plane mirror Transmission a wave behavior that is the process of allowing the wave to pass through a given point or medium Transparent a material through which light is transmitted / passes through easily Translucent a material that transmits some light but causes it to be scattered so no clear image is seen a material that does not allow light waves to be transmitted through them a wave behavior that means to take in so that the wave energy is not transferred through the medium a form of energy that moves as electromagnetic waves Opaque Absorption Light Hearing interpreting of sound waves, transmitted through the parts of the ear (outer ear, eardrum, middle ear, inner ear), by the brain Sight interpreting of light wave images, transmitted through parts of the eye cornea, lens, retina, optic nerve), by the brain different frequencies of light that are part of the visible light spectrum; the color perceived by the observer is the frequency reflected by a material, other frequencies were absorbed by the material a material that allows only certain colors of light to pass/transmit through them and absorbs or reflects all other colors the entire range of electromagnetic waves arranged in order of their frequencies or wavelengths the range of electromagnetic waves in the frequency region just below red on the visible light spectrum; when absorbed objects become warmer the range of electromagnetic waves that can be detected by the human eye including colors the range of electromagnetic waves in the frequency region just above violet on the visible light spectrum Color Color filter Electromagnetic spectrum Infrared ray Visible light Ultraviolet ray