# Science 7 reference sheet

## Inquiry
- A fair test changes or compares the intended independent variable, measures a dependent variable, and controls important alternatives.
- Accuracy = closeness to an accepted value; precision = agreement among repeated measurements.
- Separate observation, inference, claim, evidence, model, limitation, and implication.

## Evolution
- Evolution is population change across generations, not a change within one individual.
- Natural selection: heritable variation + environmental conditions + differential reproductive success → changing trait frequencies.
- Trait frequency: f=fractextcount with traittextpopulation count.
- Adaptations have no foresight; their value depends on environment.

## Matter
- Element: pure substance containing one type of atom, identified by atomic number.
- Compound: atoms of different elements chemically combined in a defined composition.
- Density: rho=fracmV.
- Crystalline solid: ordered repeating particle arrangement.
- Chemical change: atoms rearrange into new products and energy is transferred.
- Example conservation representation: 2mathrmH_2+mathrmO_2rightarrow2mathrmH_2O.

## Electricity and electromagnetism
- Current through a wire produces a magnetic field.
- A changing magnetic field through/relative to a conductor can induce current.
- Many generators: energy source → turbine/rotation → electromagnetic induction → electricity.
- Solar photovoltaic generation converts light directly to electricity without a turbine-generator stage.

## Geologic time and climate
- Relative dating gives sequence; absolute dating estimates numerical age.
- Ideal half-life model: N=N_0(frac12)^t/t_1/2.
- Fossil and climate records are incomplete; combine independent evidence and uncertainty.
- Ancient natural climate change does not imply the causes of current climate change are identical.
- First Peoples/local knowledge must retain Nation/community, place, source, and protocol context.
