Pearson Science Double Award Practical 1: Planning and Variables

A 4SD0 plan must be executable, valid and safe. Pearson assesses practical understanding in the three written Double Award papers rather than through a separate timetabled laboratory paper. This editorial skills note therefore supports the practical points embedded across Biology, Chemistry and Physics without claiming to be a Pearson-numbered unit.

Turn the question into a testable aim

Identify the relationship requested. The independent variable is deliberately changed. The dependent variable is measured in response. Write both operationally: “temperature of the enzyme mixture measured with a thermometer” is clearer than “temperature,” and “time until starch is no longer detected with iodine” is clearer than “reaction rate.”

A hypothesis predicts the direction or pattern and can include scientific reasoning. It is not a guaranteed result. If the investigation compares categories rather than a continuous range, state the groups and the measured response.

Choose a range wide enough to reveal a pattern but safe and realistic. Include at least five values for a continuous relationship when apparatus and time allow. Intervals need not be equal if the scientific question justifies closer sampling near a threshold.

Controls and fair comparison

Control variables are factors that could alter the dependent outcome. Name each important control and explain how it is maintained. “Keep volume constant” is incomplete; “deliver $10.0\ \pu{cm3}$ with the same measuring cylinder” is operational.

Biology often needs biological controls: same species, tissue region, age, starting size or acclimation time. Chemistry may require fixed reactant concentration, volume, mass, surface area and starting temperature. Physics may require fixed geometry, mass, component temperature, background conditions or reference points.

A control treatment answers whether the observed effect needs the proposed cause. An enzyme experiment may include boiled enzyme; a germination test may exclude viable seeds; a circuit investigation may use the same component under a baseline condition. A comparison is useful only if it isolates the factor of interest.