Grade 7 Science and Technology key terms

A testable prediction about what will happen in an investigation, based on observations or prior knowledge, and worded so that evidence could show it to be wrong.

Any factor in an investigation that can change or take different values. Investigators identify which ones they manipulate, which they measure, and which they hold steady.

A fair test in which only one factor is deliberately changed while all other conditions are kept the same, so any effect on the outcome can be attributed to that factor.

The degree to which repeated measurements or trials give consistent results. It is improved by repeating readings, using larger samples, and checking equipment before use.

How close a measured value is to the true value. It depends on using suitable instruments correctly, reading scales carefully, and avoiding systematic errors.

The process of assigning a number and a unit to a quantity using an instrument, such as length in centimetres or mass in grams, so results can be compared and shared.

A standard unit agreed internationally for measuring a physical quantity, for example the metre for length, kilogram for mass, second for time, and newton for force.

The idea that all matter is made of tiny particles in constant motion, with spacing and speed of motion differing between solids, liquids, and gases.

One of the physical forms a substance can take, usually solid, liquid, or gas, determined by how strongly its particles attract each other and how much they move.

The spreading of particles from a region of higher concentration to a region of lower concentration because of their random motion, without stirring or external force.

The mass of a substance per unit volume, calculated as mass divided by volume. Dense materials pack more mass into the same space and may sink in less dense fluids.

A characteristic that can be observed or measured without changing the substance into a different substance, such as colour, density, melting point, or conductivity.

A characteristic describing how a substance reacts or fails to react with other substances, such as flammability, rusting tendency, or reaction with acids.

A change in which one or more new substances form, usually with evidence such as colour change, gas production, heat release, or an odour that was not present before.

A change in appearance, shape, or state in which no new substance is produced, so the material keeps its original chemical identity.

A push or a pull acting on an object, measured in newtons. Forces can change an object's speed, direction of motion, or shape.

Two or more forces acting on an object that cancel out, producing no change in the object's motion, so it stays still or keeps moving at constant speed in a straight line.

A force that opposes motion or attempted motion when two surfaces are in contact, converting some kinetic energy into heat and sound.

The distance travelled by an object per unit of time, calculated as distance divided by time and commonly expressed in metres per second or kilometres per hour.

The energy an object has because it is moving. It increases with greater mass and increases more sharply with greater speed.

The movement of energy from one object or store to another, for example from a hot object to a cooler one, or from a moving object to the surroundings by friction.

The smallest unit of living things that can carry out all basic life processes. Organisms may consist of a single cell or many specialised cells.

The thin outer layer of a cell that controls which substances enter and leave, keeping useful materials inside and allowing waste products out.

An instrument that uses lenses to magnify objects too small to see with the naked eye, allowing observation of cells and their structures.

A group of organs that work together to carry out a major function in the body, such as digestion, breathing, or moving blood around.

A community of living organisms interacting with each other and with the non-living parts of their environment, such as soil, water, air, and sunlight.

A diagram showing how energy and matter pass between organisms in an ecosystem through the feeding relationships linking producers, consumers, and decomposers.

An organism, usually a green plant or alga, that makes its own food using light energy through photosynthesis and so supplies energy to the rest of the food web.

The variety of living things in an area, including the number of species, the genetic differences within species, and the range of habitats present.

The particular place where an organism normally lives, providing the food, water, shelter, and conditions it needs to survive and reproduce.

The continuous movement of water between oceans, atmosphere, and land through evaporation, condensation, precipitation, and run-off, driven mainly by energy from the Sun.

The spinning of an object about its own axis. Earth's rotation once every 24 hours causes the apparent daily movement of the Sun and the cycle of day and night.

The movement of one object in a path around another. Earth's yearly revolution around the Sun, with its tilted axis, produces the seasons.

A repeating cycle used to solve practical problems: define the need, research, propose solutions, build and test a prototype, evaluate results, and improve the design.

An early working model of a design, built to test whether an idea works and to reveal problems before a final product is produced.

A limit placed on a design, such as available budget, materials, time, size, safety rules, or environmental requirements, which any acceptable solution must respect.

A natural resource that is replaced by natural processes at a rate comparable to or faster than it is used, such as sunlight, wind, or sustainably managed timber.

Meeting present needs without reducing the ability of future generations to meet theirs, by limiting waste, pollution, and overuse of resources.

The release into the environment of substances or forms of energy that are harmful to living things or damaging to air, water, or soil quality.