S2.1 Exploring and designing
- Syllabus
- First assessment 2025
- Topic
- S2.1
- Level
- HL
Form Research Questions
Turn context into a question
A useful research question names a measurable relationship or comparison rather than a broad topic. Define the system, variable and conditions clearly enough that an investigation could answer it.
Use a model purposefully
A scientific model simplifies a system so it can explain observations, generate predictions or support a hypothesis. State which assumptions make the model useful.
Make a prediction
A prediction links the independent variable to an expected change in the dependent variable and gives a physical reason. It should be testable with the proposed measurements.
Common trap
Do not write a question that cannot be answered by data, and do not call a vague expectation a hypothesis without naming variables.
S2.1.1 Exam Analysis
Assessment in practice
2 marksHow it is assessed
Questions identify two reasons why a scientific model is useful.
Command terms
Identify
What earns marks
Give two distinct functions, such as prediction, explanation, visualization or simplification.
Watch for
Repeating one benefit in different words or giving a feature of a model rather than its scientific use.
Design an Investigation
Name the variables
The independent variable is deliberately changed; the dependent variable is measured; controlled variables are kept fixed. State how each will be measured or held constant.
Choose range and repeats
Use a wide enough independent-variable range to reveal the relationship, enough data points to identify a trend, and repeats to estimate random variation.
Make the method testable
Specify apparatus, sequence, resolution, timing and safety. Keep geometry and starting conditions consistent when they affect the result.
Common trap
Do not call a wider range an improvement unless it increases the evidence for the relationship, and do not change several independent variables at once.
S2.1.2 Exam Analysis
Assessment in practice
1 marksHow it is assessed
Questions identify a control variable or suggest widening a star-temperature range.
Command terms
State / Suggest
What earns marks
Name a measurable variable to keep constant, or state that a wider range improves the test of the relationship.
Watch for
Naming an uncontrolled or irrelevant quantity, or proposing more precision without improving the range.
Control Experimental Variables
Calibrate before collecting
Check zero and calibration so an offset is not mistaken for a physical effect. Record the correction and apply it consistently.
Control the conditions
Keep relevant geometry, material, dimensions, temperature, timing and applied force or pressure constant. Choose controls that could change the dependent variable.
Reduce unwanted effects
Use insulation to reduce heat loss, reduce friction or electrical resistance where appropriate, and measure background so it can be subtracted from the signal.
Common trap
Do not list “control variables” without explaining how they affect the measurement or how the method keeps them fixed.
S2.1.3 Exam Analysis
Assessment in practice
1 marksHow it is assessed
Questions ask for one variable that needs to be controlled in a materials experiment.
Command terms
State
What earns marks
Name a relevant measurable property such as material, dimensions, mass or applied rate, not an unrelated environmental condition.
Watch for
Giving an irrelevant variable such as atmospheric pressure when the method’s material and geometry are the actual controls.
Retrieve Investigation Design
Design from a question
Turn context into a measurable question, hypothesis and prediction with independent, dependent and controlled variables.
Make evidence reliable
Choose a useful range and repeats, calibrate instruments, control relevant conditions and reduce or correct known losses and background.
ConceptIB Physics HL