4th Grade Glossary
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acid rain A mild acid solution formed when rain mixes with sulfur dioxide and nitrogen oxides in the air

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.