4th Grade SCIENCE Glossary
---------------A
acid rain:
A mild acid solution formed when rain mixes with sulfur dioxide and nitrogen
oxides in the air.
Contributes to the chemical
weathering of certain kinds of rocks and minerals.
adaptation: A structure or behavior that
helps an organism survive and reproduce in its
environment.
alluvial fan: A triangular-shaped landform created when deep,
fast-moving water enters a wide, shallow area, slows down, and deposits its
sediment. Similar to a delta but forms upstream
Alpha Centauri: A
three star system, the closest to Earth.
animal:
A living being capable of movement and motor response to stimulation.
armature: The coil(s) of wire in an electric motor that rotate
through the magnetic fields of permanent magnets.
average distance: A
measurement used to calculate the difference in distance between planets.
axis:
An imaginary line, or axle, through the center of an object, about which the
object rotates.
B---------------
base level: The level at which a stream or river enters a lake or
ocean. The mouth of a stream or river is at its base level.
biceps: The large muscle at the front of the upper arm.
breakwater: An artificial barrier constructed along the shoreline to
absorb or deflect the energy of waves, thereby reducing erosion.
brush: The device in an electric motor that transfers the
electric current from the batteries to the coils of the armature by brushing up
against the lead wires.
---------------C
carrying capacity: The
greatest number of organisms of one kind that can survive in an area.
cell:
The tiny structures of which all living
centimeter: A unit of length equal to one hundredth of a meter.
chemical weathering: The process of breaking down Earth’s surface by changing
the chemical composition of rocks and minerals(for example, by acid rain or
oxidation).
chlorophyll: The green pigment in plants that allows them to
photosynthesize.
chromosome: A structure that contains an organism’s genes; located in cells.
D---------------
data:
Information collected in an experiment.
day:
The length of time a planet takes to make one complete rotation about its axis.
delta: A landform created when a river or stream reaches its base
level, slows down, and deposits its sediment; named after the Greek letter delta
(Δ) from its shape.
dependent variable:
The variable in an experiment that changes in response to
changes in the independent variable.
deposition: The
process in which particles settle to the bottom of a liquid; the release of
sediment
that occurs when a
fast-moving river or stream slows down.
diaphragm:
The muscle that separates the chest cavity from the abdominal cavity.
dike: A barrier of
earth erected to keep a river or stream from overflowing its banks. See also levee.
dominant gene: A gene that masks, or overpowers, a recessive gene; a
dominant gene is expressed when it is paired with a recessive gene. See also recessive
gene.
driven gear: The gear receiving the force.
driving gear: The gear transmitting the force.
dune: A mound of
windblown sand resulting from the constant erosion and deposition of sand by
wind.
---------------E
Earth: The third planet from the Sun in our Solar System.
electromagnet: A magnetic system consisting of a ferrous object
surrounded by coils of wire that have electric current flowing through them.
energy:
The ability to do work or to bring about change in a system or the
surroundings.
environment: The area
where a plant or animal lives.
equator: The imaginary line that divides Earth in half between the North and South Poles.
erosion: The carrying
away of weathered material by wind, water, or glaciers.
extensor: A muscle
that straightens out a body part.
F---------------
femur: The thighbone,
extending from the pelvis to the knee.
fibula:
The smaller of the two bones forming the lower leg.
flexor:
A muscle that bends a body part.
floodplain: The broad,
flat, low-lying land around rivers and streams subject to occasional flooding.
flower: The plant
structure that makes seeds in flowering plants.
force: A push on an
object; measured in newtons
fruit: A plant
structure that surrounds and protects the seeds.
---------------G
galaxy: One of
countless swirling, massive clusters of solar systems in the universe.
gear: A wheel with teeth that, when meshed with the teeth of
another wheel, is able to transmit, modify, or change the direction. of an
applied force.
gear ratio: The ratio
of the number of rotations of the driving gear to the driven gear.
gene: Tiny structures
within cells that contain the information for a trait.
germinate: To sprout
and begin to grow into a seedling.
gravitational attraction:
The force of gravity that causes objects to be attracted to one another.
gravity: The
attractive force that exists between objects.
H---------------
home range: The area where a population of animals usually forages for food.
humerus: The bone in
the upper arm, connecting the elbow to the shoulder.
hypothesis: An
educated guess about what the answer to the stated problem in an
experiment might be.
---------------I
independent variable:
The variable that is not held constant in an experiment.
inherited:
Passed from parents to children.
J---------------
joint: The place where
two adjoining bones meet.
joule: A unit of work; 1 joule of work is performed when a force
of 1 newton is used to move an object a distance of 1 meter.
Jupiter: The
fifth planet from the Sun in our Solar System.
---------------L
levee:
A continuous dike; may be human- made or natural.
leaf: A
plant structure that uses the energy in sunlight to make food.
light-year: A unit of distance, equal to the distance light travels in a
year—about9.46 trillion km.
lungs:
The basic respiratory organ of vertebrates.
M---------------
mandible:
The lower jaw bone.
map: A
scale drawing used to represent geographic locations and their relative
distances from one another.
Mars: The fourth
planet from the Sun in our Solar System.
mass: The measure of the amount of material an
object contains.
meander: A curve or
bend in a streambed or riverbed formed by slow-moving water on
gently sloping land.
mechanical energy:
Physical energy, as opposed to chemical energy.
Mercury: The planet
closest to the Sun in our Solar System.
meter: The
international standard unit of length.
Milky Way: The galaxy of
which our Solar System is a member.
millimeter: A
unit of length equal to one thousandth of a meter.
mnemonic device: A memory aid, such as a made-up sentence or rhyme, that
helps recall the order of items in a list.
moon: A
satellite of a planet.
motor: An
electromechanical device by which electric energy is transformed into
mechanical energy
muscle: Body tissues
that function in movement.
muscular system: All
the muscles in our body including muscles that move our limbs and heart.
---------------N
Neptune: The eighth
planet from the Sun in our Solar System.
newton: The
international unit of force.
North Star (Polaris) :
The star almost directly above the north pole of the Earth
Northern Hemisphere:
The half of Earth that is located north of the equator.
O---------------
orbit: The elliptical
path that a satellite travels as it moves around a star or a planet.
oxidation: The chemical reaction of rusting that occurs when certain
substances are exposed to the oxygen in air. Oxidation contributes to the
chemical weathering of certain kinds of rocks and minerals.
---------------P
particle:
A small bit of material.
patella:
The kneecap.
pelvis:
The hip bone.
permanent magnet: A
material exhibiting a magnetic field, regardless of its environment.
physical weathering: The mechanical breakdown of rocks and minerals (for
example, by wind, water, ice, changes in temperature, and plant roots).
planet:
A large, spherical satellite of a star.
plant: A living thing that produces its own food and typically
lacks locomotive movement or obvious sensory organs.
Pluto:
A dwarf planet in our Solar System.
population: A group of
organisms of one kind that lives in the same area.
producer: Green plants
that can produce food from sunlight, carbon dioxide, and water.
R---------------
radius:
The bone of the inner forearm.
ratio: A numerical representation of a relationship between two
measurements, as in a scale for a drawing or a model.
recessive
gene: A gene
that is not expressed when it is paired with a
dominant gene. See also dominant gene.
relative
brightness: The brightness of an object
when compared with the brightness of surrounding objects
relative
distance: The distance between objects
when compared with the distance between surrounding objects.
relative size: The size of an object when compared with the size of
surrounding objects
respiratory
system: Includes the lungs, trachea,
bronchi, and the channels leading to the mouth and nose; handles the body’s air
supply.
revolution: One
complete orbit of a satellite.
revolve : To travel around another object.
rib: One of a series
of bones surrounding the chest cavity of the body.
root: A plant
structure that holds a plant in place and takes in water and nutrients from the
soil.
rotation: One complete
turn of a satellite about its axis.
runoff: Running water from rain or melting snow that has not
evaporated and has not been absorbed by the ground.
---------------S
satellite: An object
in orbit around a larger object.
Saturn: The sixth
planet from the Sun in our Solar System.
scale: A proportion
used in determining the relationship between two measurements of size or
distance.
scale drawing: A
two-dimensional scaled representation of a smaller or larger object.
scapula:
The shoulder blade.
season: A short-term
weather condition that repeats on a regular basis.
sediment: Earth materials (sand, soil, rocks) carried away by
moving water and deposited when the water slows down.
seed: A plant structure that contains a tiny new plant and a
supply of food for the plant.
series circuit: A
single path by which current can flow through an electric circuit.
skeletal
system: The bones that provide support for
the body, protection for internal organs, and places of attachment for muscles.
skeleton:
All the bones that make up the supportive structure in the body of an animal
slope: The incline (upward or downward slant) of terrain.
solar system: A star and all the satellites that orbit it.
Southern Hemisphere: The half of Earth that is located south of the equator.
star: An extremely large, hot ball of glowing gas that radiates
light and heat.
stem: A plant structure that holds the leaves up to sunlight and
moves food, water, and nutrients around the plant.
sternum: The breastbone.
Sun: The star of our Solar System.
system :An
interdependent group of items that form a unified whole.
T---------------
tendon: The tissue
that connects muscle to bone.
tibia: The larger of
the two bones making up the lower part of the leg.
tidal action (tide): The periodic change (rise and fall) of the surface of the
oceans caused by the gravitational pull of the moon.
trachea: The windpipe.
trait: A physical or
behavioral characteristic of an organism.
triceps:
The large muscle at the rear of the upper arm.
---------------U
ulna:
The bone of the outer forearm.
universe: The vast space that surrounds and includes all the
galaxies as well as all other existing matter and energy
Uranus: The seventh
planet from the Sun in our Solar System.
V---------------
variable: Any factor
that can change in an experiment.
Venus: The second
planet from the Sun in our Solar System.
vertebra: One of the
bones comprising the backbone.
W--------------
wave: A rhythmic rise
and fall of the water’s surface commonly caused by the wind.
weathering: The slow process of breaking down rocks and minerals on
Earth’s surface. See also chemical weathering and physical weathering.
windbreak: A natural
or artificial barrier that reduces erosion caused by wind.
work: The transfer of
energy resulting from a force acting to move an object over a distance.
Work = Force × distance.
Y---------------
year: The length of
time a planet takes to make one complete revolution around the Sun.