ILEARN Science Grade 4 key terms

A push or a pull that can change an object's speed, direction, or shape. Forces can be strong or weak and can act when objects touch or at a distance.

A change in an object's position over time. Scientists describe motion by telling how fast and in what direction an object moves compared with a starting point.

A force that acts when two surfaces rub against each other and slows or stops motion. Rough surfaces create more friction than smooth ones.

A force that pulls objects toward each other. On Earth it pulls objects downward, which is why dropped objects fall to the ground.

How fast an object moves, measured as the distance it travels in a certain amount of time. A faster object covers more distance in the same time.

The location of an object compared with another object or a fixed reference point. Describing position often includes words like above, behind, or to the left.

The ability to cause change or do work. Energy lets objects move, grow, heat up, or give off light, and it can change from one form to another.

The energy an object has because it is moving. A heavier object or a faster object has more kinetic energy than a lighter or slower one.

Stored energy that an object has because of its position or condition. A ball held high above the ground has potential energy that becomes motion when it falls.

The movement of thermal energy from a warmer object to a cooler one. Heat always flows in one direction, from warmer to cooler, until temperatures even out.

A measure of how hot or cold something is. It tells how much thermal energy an object has, and it is measured with a thermometer.

A material that lets heat or electricity pass through it easily. Metals such as copper and aluminum are good conductors.

A material that slows or blocks the movement of heat or electricity. Rubber, plastic, and wood are common insulators used to keep energy from passing through.

A form of energy that comes from the movement of tiny charged particles. It powers lights and machines when it flows through a closed circuit.

A complete, unbroken path that electricity can flow through. If the path is broken, the electricity stops and devices such as bulbs will not light.

A form of energy that travels in straight lines and lets us see objects. Light can be reflected, absorbed, or pass through some materials.

The bouncing of light off a surface. Smooth, shiny surfaces like mirrors reflect light in a clear way, which is why we can see images in them.

A dark shape made when an object blocks light. A shadow forms on the side of the object facing away from the light source.

A form of energy made when objects vibrate. Sound travels as waves through air, water, or solids and is heard when the waves reach the ear.

A fast back-and-forth movement. Vibrating objects create sound, and faster vibrations make sounds with a higher pitch.

The stages a living thing passes through from the start of its life to the time it produces young of its own. Different organisms have different life cycles.

A big change in body form that some animals go through as they grow. Butterflies and frogs change from young that look very different from the adults.

The young produced by living things. Offspring inherit traits from their parents but are not exactly the same as either parent.

A feature or characteristic of a living thing, such as eye color, fur pattern, or leaf shape. Traits can be inherited from parents or shaped by the environment.

A trait passed from parents to their offspring through information carried in their bodies. Examples include flower color and the shape of a bird's beak.

A body part or behavior that helps a living thing survive in its environment. Adaptations develop over many generations and help organisms find food or stay safe.

Colors or patterns that help a living thing blend in with its surroundings. Camouflage makes an animal harder for predators or prey to see.

The place where a living thing lives and finds the food, water, and shelter it needs. Different habitats support different kinds of organisms.

All the living and nonliving things in an area and the ways they interact. Living parts include plants and animals; nonliving parts include water, soil, and sunlight.

The path that shows how energy passes from one living thing to another as they eat. It usually begins with a plant and ends with a predator.

A living thing, usually a plant, that makes its own food using sunlight. Producers are the starting point of most food chains.

A living thing that gets its energy by eating other living things. Animals are consumers, and they may eat plants, other animals, or both.

A living thing that breaks down dead plants and animals and returns nutrients to the soil. Mushrooms and some bacteria are decomposers.

The process plants use to make their own food. Plants take in water and a gas from the air and use sunlight to produce sugar and release oxygen.

One of the four parts of the year, each with its own typical weather and hours of daylight. Seasons happen because Earth tilts as it travels around the Sun.

The spinning of Earth on its axis. One full rotation takes about 24 hours and causes day and night.

The movement of Earth in a path around the Sun. One full trip takes about 365 days, or one year.

The shape of the lit part of the Moon that we can see from Earth. Phases change in a repeating pattern as the Moon moves around Earth.

The condition of the air and sky in a place at a certain time. Weather includes temperature, wind, clouds, and precipitation, and it can change daily.

The usual pattern of weather in a place over many years. Climate is different from daily weather because it describes long-term conditions.

The continuous movement of water between Earth's surface and the air. Water evaporates, forms clouds, falls as precipitation, and collects again.

The process in which liquid water changes into a gas called water vapor. Heat from the Sun causes evaporation from oceans, lakes, and puddles.

Water that falls from clouds to Earth as rain, snow, sleet, or hail. Precipitation is one of the main steps of the water cycle.

The movement of soil and rock from one place to another by water, wind, or ice. Erosion slowly changes the shape of Earth's surface.

The process that breaks rocks into smaller pieces over time. Water, wind, ice, and plant roots can all cause weathering.

The dropping of eroded soil, sand, or rock in a new place. Deposited material can build up to form features such as sand dunes and deltas.