PSSA Grade 5 Science key terms

Using your senses or tools to gather information about something in the natural world. An observation describes what actually happens or what you actually see, hear, or measure.

An explanation you form by combining observations with what you already know. Unlike an observation, an inference is a reasoned idea about why or how something happened.

A testable prediction that answers a science question, worded so an investigation could prove it wrong. It is written before the investigation begins and is checked against the results.

Any factor in an investigation that can change, such as time, temperature, or amount of water. A fair test changes only one variable at a time so the results can be trusted.

The part of an experiment that does not receive the treatment being tested. Comparing it with the treated group shows whether the treatment really made a difference.

The measurements and observations collected during an investigation. Data are often recorded in tables, charts, or graphs so patterns and differences can be seen clearly.

Information that supports or challenges an idea. In science, a claim must be backed by evidence gathered through careful observation or measurement, not by opinion alone.

A simplified drawing, object, or computer program that stands for something too big, too small, or too complex to study directly. Models can be changed when new evidence appears.

All the living and nonliving things in an area and the ways they interact. Energy and nutrients move among the organisms and their surroundings within an ecosystem.

A living or once-living part of an environment, such as plants, animals, fungi, and bacteria. Biotic factors interact with each other and with the nonliving parts around them.

A nonliving part of an environment, such as sunlight, water, temperature, air, and soil. These conditions help decide which organisms can survive in a place.

An organism that makes its own food, usually using sunlight, water, and carbon dioxide. Plants and algae are producers and form the base of most food chains.

An organism that cannot make its own food and must eat other organisms to get energy. Animals are consumers and may eat producers or other consumers.

An organism such as a fungus or bacterium that breaks down dead plants and animals. Decomposers return nutrients to the soil so producers can use them again.

A diagram showing how energy moves through an ecosystem when many organisms eat and are eaten. A food web is made of several food chains connected together.

A body part or behavior that helps an organism survive in its habitat, such as thick fur or migration. Adaptations build up over many generations and match organisms to their surroundings.

The process in which green plants use sunlight, water, and carbon dioxide to make sugar and release oxygen. It is the way the Sun's energy enters most food chains.

A characteristic passed from parents to offspring through genes, such as eye color in people or flower color in plants. Offspring resemble their parents because of inherited traits.

A skill or action an animal gains through experience or by watching others, such as a bird learning a song. It is not passed to offspring through genes.

Anything that has mass and takes up space. Matter is found as solids, liquids, and gases, and it can be described and measured by its properties.

The amount of matter in an object, usually measured in grams or kilograms with a balance. Mass stays the same even when the object changes shape or moves elsewhere.

The amount of space an object or substance takes up, often measured in milliliters, liters, or cubic centimeters. It can be found by measuring container size or water displacement.

How much mass is packed into a given amount of space. An object sinks in a liquid when its density is greater than the density of that liquid.

A change in the size, shape, or state of matter that does not create a new substance. Melting ice, tearing paper, and dissolving sugar are examples.

A change that produces one or more new substances with properties different from the originals. Burning wood, rusting iron, and baking a cake are examples.

A combination of two or more substances that keep their own properties and can usually be separated by physical means. Trail mix and salty water are mixtures.

A push or a pull that can change an object's speed, direction, or shape. A force is described by how strong it is and which way it points.

A force that resists motion when two surfaces touch and slide past each other. Friction makes heat and can slow down or stop a moving object.

The ability to cause change or do work. Energy appears as motion, heat, light, sound, and stored forms, and it can move from one object to another.

A complete, unbroken path that electric current can flow through. If the path is broken, current stops and the bulbs or motors in the circuit turn off.

The slow breaking down of rock and other earth materials into smaller pieces by water, wind, ice, or plant roots. The broken pieces stay where they form.

The picking up and carrying away of weathered rock, soil, and sand by moving water, wind, or ice. Erosion moves material from one place to another.

The dropping of eroded soil, sand, or rock in a new place when moving water, wind, or ice slows down. Deposited material builds up landforms such as deltas and dunes.

The continuous movement of water between Earth's surface and the air through evaporation, condensation, precipitation, and collection. The same water is reused again and again.

The change of liquid water into water vapor, a gas, when it gains heat energy. Evaporation happens from oceans, lakes, rivers, and puddles and adds vapor to the air.

The change of water vapor into tiny liquid droplets when the air cools. Condensation forms clouds, fog, and the drops on a cold glass.

The spinning of an object around its own axis. Earth's rotation once every 24 hours causes day and night as different sides face the Sun.

The movement of one object in a curved path around another object. Earth's revolution around the Sun takes about one year and helps cause the seasons.

A natural resource that nature replaces in a fairly short time, such as sunlight, wind, moving water, and trees that are replanted. People try to use these resources wisely and reuse them.

A natural resource that exists in limited amounts and cannot be replaced quickly, such as coal, oil, and natural gas. Once these are used up, they are gone for a very long time.