GACE Middle Grades Science (705) key terms

The process of asking testable questions, designing investigations, gathering and analyzing evidence, and constructing explanations that are revised as new evidence appears. It includes communication and peer review of results.

A testable, tentative explanation or prediction about a natural phenomenon, stated so that observations could support or contradict it. It differs from a theory, which is broader and well supported.

A broad, well-tested explanation for a body of evidence that has survived repeated investigation and is widely accepted by the scientific community. Theories organize laws and observations rather than being guesses.

A concise statement, often mathematical, describing a consistent regularity observed in nature, such as the law of conservation of mass. Laws describe patterns; they do not by themselves explain underlying mechanisms.

Any factor in an investigation that can change or take different values. Investigators classify variables as independent, dependent, or controlled to keep track of what is being manipulated and measured.

The factor that the investigator deliberately changes or manipulates in an experiment to observe its effect. It is sometimes called the manipulated variable and is plotted on the x-axis of a graph.

The factor that is measured or observed in response to changes in the independent variable. It is sometimes called the responding variable and is plotted on the y-axis of a graph.

An investigation in which all variables except the independent variable are held constant, so any change in the outcome can be attributed to the manipulated factor rather than to confounding influences.

The comparison group in an experiment that does not receive the treatment being tested. It provides a baseline against which the effects observed in the experimental group can be judged.

Information obtained through direct observation, measurement, or experiment rather than through reasoning alone or appeals to authority. Scientific claims must be supported by such evidence and be open to verification.

Recorded observations and measurements collected during an investigation. Data may be quantitative, such as numbers and units, or qualitative, such as descriptions, and are analyzed to support or reject a hypothesis.

Repeating an investigation, ideally by other researchers or with new samples, to see whether the same results are obtained. Consistent replication strengthens confidence that findings are reliable rather than accidental.

Critical evaluation of research by independent experts in the same field before publication or funding. It checks methods, reasoning, and evidence, helping to filter out flawed or unsupported claims.

A systematic distortion in design, measurement, sampling, or interpretation that pushes results in a particular direction. Bias differs from random error because it does not average out with repeated trials.

The number of individuals or trials included in a study. Larger samples generally reduce the influence of chance variation and make estimates and comparisons more trustworthy.

A visual display of data, such as a line, bar, or scatter plot, chosen to reveal patterns and relationships. Axes should be labeled with quantities and units, and scales should be consistent.

The theory that Earth's rigid outer shell is divided into plates that move over the softer mantle. Their interactions at boundaries explain earthquakes, volcanoes, mountain building, and the distribution of continents.

A plate boundary where two plates move toward each other. Depending on the crust involved, the result may be subduction with volcanic arcs and deep trenches, or continental collision forming high mountains.

A plate boundary where two plates move apart, allowing magma to rise and form new crust. It produces mid-ocean ridges under oceans and rift valleys on continents, accompanied by shallow earthquakes.

The process in which one tectonic plate sinks beneath another at a convergent boundary. It generates deep ocean trenches, earthquakes, and chains of volcanoes, and recycles oceanic crust into the mantle.

Ground shaking caused by the sudden release of accumulated strain along faults in Earth's crust. Energy travels as seismic waves, and the focus depth and distance affect the shaking felt at the surface.

The set of processes that transform material among igneous, sedimentary, and metamorphic rocks through melting, cooling, weathering, erosion, deposition, compaction, and heat and pressure.

The transport of weathered rock and soil material by agents such as water, wind, ice, and gravity. Erosion differs from weathering, which breaks material down in place without moving it.

The continuous movement of water among oceans, atmosphere, land, and living things through evaporation, transpiration, condensation, precipitation, infiltration, and runoff. Solar energy and gravity drive the cycle.

Weather is the short-term state of the atmosphere at a place, while climate is the pattern of weather averaged over decades. Climate is influenced by latitude, altitude, oceans, and greenhouse gases.

The warming of a planet's surface as certain atmospheric gases absorb and re-emit outgoing infrared radiation. It keeps Earth habitable, though human-added gases intensify it and drive global warming.

The arrangement and motions of Earth, the Sun, and the Moon that produce day and night, seasons, tides, and the phases of the Moon. Orbital tilt and revolution explain yearly seasonal changes.

The Sun and all bodies bound to it by gravity, including planets, moons, asteroids, and comets. Inner planets are small and rocky, while outer planets are large and rich in gas and ice.

The attractive force between objects with mass, increasing with mass and decreasing with distance. It governs orbits, tides, and falling objects and shapes the large-scale structure of the universe.

The principle that all living things are made of one or more cells, that the cell is the basic unit of life, and that new cells arise from existing cells through division.

A selectively permeable barrier of lipids and proteins surrounding a cell. It controls what enters and leaves and supports communication, and it is described by the fluid mosaic model.

The net movement of particles from an area of higher concentration to one of lower concentration, driven by random motion. It requires no added energy and is one way cells exchange materials.

The process by which plants, algae, and some bacteria use light energy to convert carbon dioxide and water into sugars and oxygen. It stores energy and supplies the base of most food webs.

The set of reactions in which cells break down sugars, using oxygen in aerobic cases, to release usable energy and produce carbon dioxide and water. It complements photosynthesis in ecosystems.

A form of cell division that produces two genetically identical daughter cells, supporting growth, repair, and asexual reproduction. It involves chromosome duplication and orderly separation of chromosomes.

The study of heredity and the variation of inherited traits, including how genes on chromosomes are transmitted and expressed. It explains patterns such as dominance and independent assortment.

The process by which heritable traits that improve survival and reproduction become more common in a population over generations. It requires variation, inheritance, and differential reproductive success.

A heritable feature or behavior that improves an organism's ability to survive and reproduce in its environment. Adaptations arise through natural selection over many generations, not by choice.

A community of organisms interacting with one another and with their physical environment, including the flow of energy and cycling of matter. Ecosystems can be studied at many scales.

A model of feeding relationships in an ecosystem that shows how energy and matter pass from producers to consumers and decomposers. Arrows indicate the direction of energy transfer.

The tendency of living systems to maintain relatively stable internal conditions, such as temperature or pH, despite external changes. It relies on feedback mechanisms that detect and correct deviations.

The smallest unit of an element that retains the element's properties, consisting of a nucleus of protons and neutrons surrounded by electrons. Atoms combine in fixed ratios to form compounds.

A pure substance made of only one kind of atom, defined by its atomic number. Elements cannot be broken down into simpler substances by ordinary chemical means.

A substance formed when two or more elements combine chemically in fixed proportions, with properties different from those of the constituent elements. Water and carbon dioxide are familiar examples.

An arrangement of the elements by increasing atomic number that groups them by recurring chemical properties. Position reveals patterns such as reactivity, atomic size, and metallic character.

A process in which substances are transformed into new substances through the breaking and forming of chemical bonds. Atoms are conserved, so total mass stays the same in a closed system.

The principle that matter is neither created nor destroyed in ordinary chemical and physical changes. In a closed system, the total mass of reactants equals the total mass of products.

The movement of energy from one object or system to another, as through heat, work, light, or sound. Energy may change form but the total in an isolated system is conserved.

A push or pull that can change an object's motion, direction, or shape, measured in newtons. Forces combine as vectors, and a net force of zero means no change in motion.

Three principles describing how forces affect motion: objects resist changes in motion, net force causes acceleration proportional to mass, and every action has an equal and opposite reaction.

A disturbance that transfers energy through space or a medium without transporting matter. Waves are described by amplitude, wavelength, frequency, and speed, and may be transverse or longitudinal.

The full range of electromagnetic radiation arranged by wavelength and frequency, from radio waves through visible light to gamma rays. Visible light occupies only a small portion of the range.

Ongoing checks of student understanding during instruction, used to adjust teaching and give feedback. Examples include questioning, exit tickets, and quick concept probes rather than graded unit tests.

An evaluation of student learning at the end of a unit or course, used to judge achievement against standards. It typically yields a score or grade and may include projects, tests, or performance tasks.

An evaluation in which students demonstrate knowledge and skills by completing a realistic task or product, such as designing an investigation. Scoring usually relies on explicit criteria in a rubric.

A scoring guide that lists criteria and describes levels of quality for a task or product. It makes expectations transparent and supports consistent, objective grading of open-ended work.

Teaching in which students learn science by posing questions, planning and carrying out investigations, analyzing data, and constructing evidence-based explanations, with the teacher guiding rather than simply telling.

A persistent, incorrect idea that students bring to learning and that resists simple correction. Effective instruction elicits such ideas and provides evidence and experiences that challenge them.