Science Definitions for Fourth Grade

  1. Work- The use of force to move an object over a distance.
  1. Wheel and Axle-A simple machine made of a wheel and an axle that turn together.
  1. Weight- A measure of the gravitational force acting on an object.
  1. Wedge- A simple machine made of two inclined planes placed back to back. A knife for instance.
  1. Weather-The condition of the atmosphere at a certain place and time.
  1. Water Vapor- The gas form of water.
  1. Water Cycle-The constant movement of water from the surface of Earth to the air and back again.
  1. Volume- The LOUNDNESS of a sound. (or softness).
  1. Vibration- A quick back and forth movement of matter. Base cause of sound.
  1. Velocity- The measure of the speed and direction of motion of an object. The car is moving 90 mph to the east.
  1. Universe- Everything that exists in space.
  1. Transparent- Allowing light to pass through. A clear window for instance.
  1. Translucent- Allowing only some light to pass through. Notebook paper.
  1. Sun- The star at the center of our solar system. Seems largest to us because it is the closest star to us. Highest in apparent magnitude.
  1. Star- A huge ball of very hot burning gases in space.
  1. Standard Measure- An accepted unit of measure. In science we often use the metric system instead of the customary system of measurement.
  1. Speed-The measure of the change in an objects position in a unit of time. 50 miles per hour.
  1. Solar System- A star and all the planets and other objects that revolve around it.
  1. Simple Machine- A machine with few or no moving parts that you apply just one force to.
  1. Screw- A simple machine made of a post with an inclined plane wrapped around it.
  1. Scientific Method- An organized plan that scientists follow to test their hypothesis.
  1. Scale- The size of the units on a bar or line graph.
  1. Rotate- To spin around an axis. The earth rotates on its axis.
  1. Revolve- To travel in a closed path. The earth revolves around the sun.
  1. Refraction- The bending of light as it moves from one material to another. A pencil in a glass of water looks broken because of refraction.
  1. Reflection- The bouncing of light off an object.
  1. Pulley-A simple machine that consists of a wheel with a line around it.
  1. Producer- A living thing, such as a plant, that can make its own food.
  1. Prey- Consumers that are eaten by predators.
  1. Prediction- A statement of what will happen. Based on observations and knowledge of cause and effect relationships.
  1. Predator- A consumer that eats prey.
  1. Precipitation- Water that falls from clouds to earth’s surface. Rain, snow, sleet.
  1. Position- The location of an object. The earth is in the third position from the sun.
  1. Population- All the individuals of one kind living in an ecosystem.
  1. Planet- A large body that revolves around a star.
  1. Pitch- How high or low a sound is.
  1. Phase- One of the shapes the moon seems to have as it orbits Earth.
  1. Orbit-The path of one object in space around another object. Earth around the sun.
  1. Opaque- Not allowing light to pass through.
  1. Omnivore- An animal that eats both plants and other animals.
  1. Observation-Information that you gather with your senses.
  1. Niche- The role a living thing plays in its habitat.
  1. Motion- A change in position of an object. The boy and his bike are in MOTION.
  1. Moon- A natural body that revolves around a planet. It takes one month for the moon to revolve around the Earth.
  1. Migration- The movement of animals from one region to another and back again.
  1. Microscope-A science tool that makes tiny things look bigger.
  1. Meteorology- The study of weather.
  1. Lever- A simple machine made of a bar that pivots on a fixed point.
  1. Interpret- To evaluate evidence or data in order to draw a conclusion.
  1. Inference- An untested interpretation of observations.
  1. Inertia- The property of matter that keeps an object at rest or moving in a straight line until redirected by a new force.
  1. Inclined Plane- A simple machine that is a slanted surface.
  1. Hypothesis- A scientific explanation that can be tested. (Experiments)
  1. Hygrometer- An instrument for measuring humidity.
  1. Humidity-A measurement of the amount of water vapor in the air.
  1. Hibernation- A dormant, sleep or inactive state in which normal activities slow down.
  1. Herbivore- An animal that eats only plants.
  1. Habitat- An environment that meets the needs of an organism.
  1. Gravity-The force of attraction between Earth and other objects. Always down.
  1. Gravitation- The pull of all objects in the universe on one another.
  1. Galaxy- A grouping of gas, dust, and many stars, plus any objects that revolve around those stars.
  1. Fulcrum- The fixed balance point on a lever. Mid point of a see-saw.
  1. Front-The border where two air masses meet.
  1. Friction- A force that resists motion between objects that are touching.
  1. Frequency- The number of vibrations in a unit of time. Humans can hear between 20-20,000 vibrations per second.
  1. Force- A pull or push that causes an object to move, stop, or change direction. Overcomes inertia.
  1. Food Web- A group of food chains that overlap.
  1. Food Chain- A series of organisms that depend on one another for food. Food chains begin with a producer.
  1. Extinction- The death of all the members of a certain group of organisms.
  1. Experiment- A controlled test of a hypothesis.
  1. Evaporation- The process by which a liquid changes into a gas.
  1. Estimate- A careful guess about the amount of something.
  1. Environment- All of the living and non living things surrounding an organism.
  1. Energy Pyramid- A diagram showing how much energy is passed from one organism to the next in a food chain.
  1. Ecosystem-A community of living things and the community’s physical environment.
  1. Decomposer- A living thing that feeds on the wastes and remains of plants and animals.
  1. Current- A stream of water that flows like a river through the ocean.
  1. Convex lens- A lens that is thicker at the center than at the edges. Light waves are brought together by a convex lens.
  1. Consumer- A living thing that can’t make its own food and must eat other living things.
  1. Constellation- A pattern of stars that form an imaginary picture or design in the sky.
  1. Condensation- The process by which a gas changes into a liquid.
  1. Concave Lens- A lens that is thicker at the edges than in the center. Light waves are spread apart as they pass through a concave lens.
  1. Community- All the populations of organisms living in an environment.
  1. Comet- A ball of ice, rock, and frozen gases that orbits the sun.
  1. Climate- The pattern of weather an area experiences over a long period of time.
  1. Carnivore- An animal that eats only other animals.
  1. Camouflage- A color or shape that helps an animal hide.
  1. Biotic- Describes a living part of an ecosystem.
  1. Basic needs- Food, water, air and shelter that an organism needs to survive.
  1. Barometer- An instrument for measuring air pressure.
  1. Axis- An imaginary line that runs through the center of the Earth from the North Pole to the South Pole. Earth’s tilted axis is responsible for seasonal changes in the climate.
  1. Anemometer- An instrument for measuring wind speed.
  1. Air mass- A large body of air that has similar temperature and humidity throughout.
  1. Adaptation- A body part or behavior that helps and organism survive.
  1. Acceleration- Any change in the speed or direction of an object’s motion.
  1. Abiotic- Describes a non living part of an ecosystem. Water and rocks for an example.