IGCSE Physics Practical Skills 4: Planning and Evaluation
A Cambridge IGCSE Physics framework for planning investigations, choosing variables and ranges, controlling measurements, analysing data, and writing specific evaluations for 06...
A physics investigation should test one relationship with measurements capable of showing whether that relationship is present. Planning is therefore about evidence, not merely listing apparatus.
These original notes support Cambridge IGCSE Physics 0625 and 0972 practical assessment without reproducing an examination task.
Convert the question into variables
Write the investigation as:
How does the independent variable affect the dependent variable when the relevant control variables are kept constant?
Then define how each variable will be changed or measured.
For a cooling investigation:
- independent variable could be the insulation thickness
- dependent variable could be temperature decrease after a fixed time
- controls could include liquid volume, container, starting temperature, room conditions, and time interval
Naming a control is not enough. Say how it will be kept constant.
Select apparatus by range and resolution
Choose equipment that can measure the expected values safely and distinguish meaningful changes.
- A ruler must be long enough for the largest length.
- A stopwatch method must produce an interval large compared with reaction time.
- A meter range must contain the expected electrical reading.
- A thermometer must cover the expected temperatures with useful scale divisions.
When justifying a choice, connect the instrument property to the measurement. "More accurate" alone is incomplete.
Use enough values
Several values across a suitable range reveal a relationship better than only two end points. Choose intervals that are practical to set and measure.
The range should not:
- exceed equipment limits
- create an unsafe condition
- make the response too small to resolve
- make the response happen too quickly to measure
If a preliminary reading shows that the range is unsuitable, refine it before collecting the full set.
Write the method in operational order
A repeatable plan states:
- how the apparatus is assembled and aligned
- how the independent variable is set and measured
- how control variables are held constant
- when measurement begins and ends
