Science: Science Ideas and Their Implications
This section covers the Science domain of NCEA Level 1, whose achievement standards ask you to explain science ideas and then investigate their implications for everyday life - for example, the cost, safety and environmental effects of using electricity and magnetism. Strong answers name the science idea correctly, support claims with data, and state implications that are specific and balanced.
Science ideas you must use precisely
- Energy and power: power is the rate of transferring energy, P = E/t, so E = Pt. Household electrical energy is billed in kilowatt-hours (kWh): a 2 kW appliance running 3 hours uses 6 kWh.
- Circuits and magnetism: V = IR links voltage, current and resistance. A current-carrying coil around an iron core makes an electromagnet; its strength increases with more current and more turns. Electromagnets are switchable, which is why they suit cranes, relays and door locks.
- Chemistry: the particle model explains states, diffusion and expansion; in a reaction atoms are rearranged, not created or destroyed.
- Biology: cells carry out life processes; photosynthesis stores energy (carbon dioxide + water + light → glucose + oxygen) and respiration releases it; energy is lost at each step of a food chain.
Investigating implications
Identify the independent variable you change, the dependent variable you measure, and the variables held constant. Repeat trials, average them, and flag anomalies. Reliability comes from repeats; validity comes from controlling variables so you measure what you claim to measure.
Worked example
A 2 kW fan heater runs for 5 hours. Energy = 2 kW × 5 h = 10 kWh. At 30 cents per kWh the cost is 10 × 0.30 = $3.00. A heat pump delivering the same heat with a coefficient of performance of 3 uses 10 ÷ 3 ≈ 3.3 kWh, about $1.00. Implication: the heat pump costs less to run and emits less carbon dioxide per unit of heat, but has a higher purchase price, so the recommendation depends on how much the heater is used.
Traps that cost marks
- Mixing up power (kW) and energy (kWh), or dropping units.
- Writing “it is better for the environment” without naming the effect.
- Giving a conclusion that does not refer back to the hypothesis and the data.
- Calling a test reliable when variables were not controlled - that is a validity problem.