S1.1 Experimental techniques
- Syllabus
- First assessment 2025
- Topic
- S1.1
- Level
- HL
Learning objectives
Address Safety, Ethics and Environment
Move from hazard to control
Identify the specific hazard, who or what could be harmed, and how exposure could occur. Then choose a control that removes the hazard or reduces probability or severity—for example shielding and distance for ionizing radiation, insulation for hot equipment, or containment for pollutants.
Protect self, others and the environment
Check the investigator, nearby people, organisms, equipment and surroundings. After applying controls, state any residual risk and whether the investigation should proceed, be redesigned or not be performed.
Frame an ethical choice
Compare benefits and harms for the affected people. For a medical isotope, balance possible treatment benefit against side effects and the consequence of not treating; do not present a medical choice as risk-free.
Discuss rather than list
A discussion needs more than one perspective or consequence and a reasoned comparison. For environmental questions, consider extraction, use, disposal and long-term effects.
Common trap
Do not write a vague claim such as “it is dangerous.” Name the mechanism and the consequence, then connect it to the decision.
S1.1.1 Exam Analysis
This exam question is unavailable.
Measure with Suitable Precision
Choose and prepare the instrument
Match range and resolution to the expected value and required precision. Check calibration, zero, units and viewing geometry before measuring mass, time, length, volume, temperature, force, current, potential difference, angle, sound intensity or light intensity.
| Variable | Suitable instrument or method | Precision check |
|---|---|---|
| Mass; time | Balance; timer or data logger | Resolution is small enough for the expected change |
| Length; volume | Ruler/caliper/micrometer; measuring cylinder/burette | Avoid parallax and use the correct meniscus/zero |
| Temperature; force | Thermometer/probe; force meter | Use a suitable range and allow the reading to stabilize |
| Current; potential difference | Ammeter; voltmeter | Connect correctly and select a safe range |
| Angle; sound/light intensity | Protractor; calibrated sensor | Align the reference and control position/orientation |
Read the value
Record enough digits to reflect the instrument’s resolution and include the unit. For a corrected reading, apply the zero offset with the correct sign; a displayed value is not automatically the true value.
Worked example — signed zero correction
A caliper shows 20.60mm around a sphere but reads −0.30mm when closed. True diameter =20.60−(−0.30)=20.90mm. Subtract the zero reading algebraically; do not guess the correction direction.
Improve reliability
Repeat measurements, average them, and measure at different positions or orientations when geometry permits. This reveals random variation and reduces its effect on the mean.
Common trap
Do not increase precision by writing extra decimal places that the instrument cannot resolve, and do not correct a zero error in the wrong direction.
S1.1.2 Exam Analysis
This exam question is unavailable.
Retrieve Experimental Practice
Evaluate responsibly
Name the physical hazard or ethical trade-off and connect it to consequences and benefits.
Measure honestly
Check zero, units and resolution; repeat suitable measurements, average them and report only justified precision.