| Term | Definition |
| Cycle | a series of events that repeats |
| Variable | something that changes in an experiment and affects the results of the experiment (only 1 can be changed) |
| System | a group of objects working together |
| Matter | anything that has mass and takes up space |
| Physical Properties | properties that can be observed by the senses without changing the substance |
| Mass | the amount of matter in an object |
| Weight | the pull of gravity on an object |
| Volume | the amount of space in an object |
| Density | the concentration of matter in an object |
| Solution | a combination of substances that cannot be easily separated |
| Mixture | a combination of substances that can be easily separated into its own parts |
| Solubility | the ability to dissolve |
| Solid | anything that has a definite volume and shape |
| Liquid | anything that has a definite volume but no definite shape |
| Gas | anything that has no definite volume or shape |
| Evaporation | changing from a liquid to a gas |
| Condensation | changing from a gas to a liquid |
| Melting | changing from a solid to a liquid |
| Boiling | when heat is applied to change from liquid to a gas |
| Freezing | changing from a liquid to a solid |
| Boiling Point | the temperature at which a substance boils |
| Freezing/Melting Point | the temperature at which a substance transitions from a solid to a liquid |
| Individual | a single organism |
| Fossils | remains of once living organisms that have been preserved |
| Conductor | any material that allows heat or electricity to pass through it |
| Electric Circuit | any path along which electrons can flow |
| Lens | a piece of clear material that bends light rays passing through it |
| Insulator | any material that does not allow heat or electricity to pass through |
| Electromagnet | a magnet formed by the flow of an electric current |
| Refraction | the bending of light rays |
| Reflection | light that bounces off an object |
| Population | all the individuals of the same kind living in the same environment |
| Community | all the populations of organisms living together in an environment |
| Ecosystem | a community and its physical environment together |
| Habitat | a place in an ecosystem where a population lives |
| Niche | the role each population has in its habitat |
| Producer | an organism that makes its own food (plant) |
| Consumer | an organism in a community that must eat to get the energy it needs |
| Decomposer | consumer that breaks down the tissues of dead organisms (bacteria, mushrooms, vulture) |
| Food Chain | the ways in which the organisms in an ecosystem interact with one another according to what they eat |
| Symbiosis | a long-term relationship between different kinds of organisms |
| Instinct | a behavior that an organism inherits |
| Learned Behavior | a behavior that an animal learns from its parents |
| Inherited Trait | a characteristic that is passed from parent to offspring |
| Adaptation | a characteristic an organism develops to aide in survival |
| Direct Development | a kind of growth where organisms keep the same body features as they grow larger |
| Incomplete Metamorphosis | a three-step process including a change in an organism's body as it grows (egg, nymph, adult) |
| Complete Metamorphosis | a four-step process including a change in an organism's body as it grows. (egg, larva, pupa, adult) |
| Biome | a region of the world that is defined by its climate and the unique plants and animals that live there |
| Bacteria | tiny living cells that "fix" nitrogen in the soil |
| Decay | the slow, natural breaking down of plant and animal matter |
| Fish | vertebrates that live their entire life in water |
| Fossil Fuel | a fuel formed from the remains of once-living organisms |
| Germinate | the sprouting of seeds |
| Greenhouse Effect | process by which the Earth's atmosphere absorbs heat |
| Respiration | the process that releases energy; Inhale oxygen exhale carbon dioxide |
| Fungi | living things that look like plants but cannot make their own food: mushrooms |
| Nitrogen Cycle | the cycle in which nitrogen gas is changed into forms of nitrogen that plants can use |
| Photosynthesis | the process by which plants make their own food |
| Recycling | the process of taking a resource from a product and making it into a new item |