Download waves

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