1.2.1(a)-(c) - Investigative approaches, risk and written instructions
This lesson is about practical competence: how to move from a biological question to a safe, workable method, and how to carry it out without losing control of the investigation. You will learn how to apply investigative approaches, solve practical problems, use equipment and materials safely, identify hazards and minimise risk, and follow written instructions accurately. These are not separate "lab rules"; they are the habits that make practical evidence trustworthy.
Investigative Thinking
An investigative approach means making sensible practical decisions so that a method can answer a question. It is more than copying a recipe. In a practical context, you may need to choose materials, quantities, variables to measure, variables to control, timings, apparatus, and a safe sequence of steps.
Investigative approach
A practical way of solving a scientific problem by choosing suitable methods, apparatus, measurements and controls for the question being investigated.
The key test is whether each decision helps the investigation answer the aim. If the aim is to find whether one factor affects a biological measurement, the method should make that factor the one being deliberately changed, while other important conditions are kept as constant as possible.
For this lesson, keep the focus on the practical decisions themselves. Detailed experimental design, full data processing, graphing and evaluation are taught in neighbouring Module 1 lessons; here the target is the competence of applying a method in a practical setting.
From brief to practical decisions
A student is given this brief: "Investigate how temperature affects the time taken for a biological colour change."
A competent investigative approach could include:
- Choose the independent variable: temperature.
- Choose the dependent variable: time taken for the colour change.
- Control key conditions: same volume of sample, same volume of reagent, same starting concentration, same endpoint for judging the colour change.
- Choose suitable apparatus: thermometer or temperature probe, water bath or beaker of water at known temperature, timer, test tubes and a measuring device suitable for the volumes.
- Plan safe handling: avoid burns from hot water, wear eye protection if reagents are irritants, and dispose of materials as instructed.
The biology of the colour change is not the main point here. The main point is that the practical decisions match the question.
Now try applying the same decision-making pattern to a new practical brief.
Solving Practical Problems
Practical work rarely behaves like a perfect written plan. Equipment may be limited, a measurement may be hard to judge, a result may take longer than expected, or a method may not give a clear endpoint. Applying investigative approaches includes noticing these issues and making adjustments that still preserve the aim, safety and fairness of the investigation.
A practical problem should be handled in this order:
| Decision | What to ask | Good practical response |
|---|---|---|
| Aim | What question am I trying to answer? | Keep the adjustment linked to the original aim. |
| Measurement | What exactly will I measure or observe? | Choose a clear endpoint, unit or observation rule. |
| Apparatus | Is the apparatus suitable for the scale and precision needed? | Use the most appropriate measuring device available. |
| Variables | What might affect the result besides the factor I am changing? | Keep important conditions constant where possible. |
| Safety | Does the adjustment introduce a new hazard or change the risk? | Add a specific control or ask before continuing. |
For example, if a method asks for 1.0 cm3 of solution but only a large beaker is available, the beaker is not suitable for measuring that small volume accurately. A better choice would be a pipette or syringe if provided. If neither is available, the correct response is not to guess and hope; it is to report the issue and decide, with supervision, whether the method can still produce useful evidence.
For practical problem-solving, do not write only "use better equipment" or "be more careful". Name the equipment or action and explain what it improves, such as safety, accuracy, precision, control of a variable, or clarity of the endpoint.
The next check asks you to connect an apparatus choice to the scale of the measurement.
Hazards, Risks and Controls
Safe practical work starts with distinguishing hazard from risk. Students often write "wear goggles" as the hazard, but that is a control measure, not the source of harm.
Hazard
Something with the potential to cause harm, such as hot water, a sharp instrument, an irritant chemical, broken glass, a microorganism, or an electrical supply near liquid.
A hazard exists before you decide how likely harm is in the practical.
Risk
The chance that harm will occur from a hazard, together with how serious the harm could be in the actual practical context.
A control measure is a specific action that reduces the risk. Good risk minimisation usually names both the hazard and the control. "Wear eye protection" is better than "be safe", but "wear eye protection because the reagent is an irritant that could splash into the eyes" is stronger because it links the control to the hazard.
| Practical context | Hazard | Risk | Specific risk minimisation |
|---|---|---|---|
| Heating water for a biological sample | Hot water or hot glassware | Burns or scalds | Use a water bath or heatproof mat, handle hot tubes with a holder, allow cooling before handling. |
| Cutting plant material | Sharp blade or scalpel | Cuts to fingers | Cut away from the body on a stable surface, use the blade only as instructed, return it safely after use. |
| Using an irritant stain or reagent | Irritant chemical | Irritation to eyes or skin | Wear eye protection, avoid direct contact, clean spills as instructed, dispose of solution safely. |
| Working with microorganisms | Live cultures and contaminated materials | Contamination or exposure | Use aseptic technique only when trained, keep containers closed as instructed, disinfect benches, dispose of cultures correctly. |
OCR does not require this lesson to become a health-and-safety law lesson. The practical skill is to identify potential hazards in the practical being carried out and understand how to minimise the risks involved.
Writing a risk-control point
Weak answer: "Wear goggles."
Better answer: "The reagent is an irritant, so wear eye protection and avoid splashing when transferring it."
Why it improves: the better answer identifies the hazard, states a specific control, and explains how the control reduces risk.
Use the same three-part structure when you answer practical risk questions.
Safe and Correct Use
Using equipment safely and correctly means more than avoiding injury. It also affects the quality of the evidence. If equipment is used outside its intended range, read from the wrong position, assembled insecurely, or used before the student understands the safe handling routine, the method can become unsafe and the results can become unreliable.
Correct use usually includes four habits:
- Check the equipment is suitable for the measurement or technique.
- Use the equipment in the demonstrated way and in the correct sequence.
- Use any safety equipment or handling routine linked to the material or technique.
- Dispose of materials and clean the workspace as instructed.
This competence should become increasingly independent. Early in the course, a teacher or technician may demonstrate a new technique. By the end of the course, a student should use common laboratory equipment and materials safely with minimal prompting, while still asking when a hazard, method or result is unclear.
Specific examples help, but do not over-generalise. Eye protection may be needed for splash risks; gloves may be needed for some irritants or biological materials; direct supervision may be needed for higher-risk materials; smaller volumes or lower concentrations may reduce risk. The correct control depends on the actual practical.
Safe and correct use is a combined skill: choose suitable apparatus, use it as instructed, manage hazards, and keep the method capable of producing valid evidence.
Following Written Instructions
Written instructions protect both safety and validity. They tell you the aim, quantities, sequence, timings, temperatures, safety controls and checkpoints. If a student changes a step without understanding why it is there, they may change the variable being tested, create a hazard, or make the results impossible to compare.
A strong way to follow written instructions is:
- Read the aim first, so you know what the method is trying to find out.
- Read the full method before starting, especially safety notes and disposal instructions.
- Identify exact quantities, units, timings and temperatures.
- Set out apparatus in the order it will be used.
- Follow the sequence step by step, ticking or tracking steps as you complete them.
- Stop and ask if an instruction is unclear, impossible with the apparatus provided, or appears unsafe.
The instruction sequence often matters. "Add the reagent, then start the timer immediately" is not just wording; it standardises the time point. "Use the same volume each time" controls a variable. "Do not exceed 40 degrees C" may protect safety, the biological material, or the validity of the comparison.
Following Written Instructions Continued
Written instructions do not remove the need to think. If a tube cracks, a reagent is missing, a spill occurs, or the apparatus does not match the method, the correct practical response is to pause. Continuing by improvising may be unsafe or may invalidate the investigation.
Bringing the Skills Together
In a competent practical, the three skills in this lesson work together.
| Skill | What it looks like in practice | Common weak version |
|---|---|---|
| Apply investigative approaches | Choose variables, measurements, apparatus and safe procedure that answer the aim. | Copy steps without knowing what they test. |
| Use equipment and materials safely and correctly | Use the demonstrated technique, manage hazards and choose specific controls. | Say "be careful" without naming a hazard or control. |
| Follow written instructions | Use the aim, sequence, quantities, timings and safety notes accurately. | Skip ahead, estimate quantities, or change steps without checking. |
A practical judgement
A written method says to heat three tubes of biological sample at different temperatures for five minutes before adding the same volume of reagent to each tube. A student notices that one tube has less sample than the others.
Good judgement: do not continue as if the tubes are comparable. The sample volume is a condition that should be kept constant. The student should correct the volume if the method and supervisor allow it, or repeat that tube using the correct volume. They should also keep the heating time and reagent volume the same so that temperature remains the planned independent variable.
This is the practical mindset OCR is targeting: not panic, not guesswork, and not blind obedience. The student should understand enough of the aim, method and safety controls to carry out the investigation methodically and to recognise when a practical issue needs a reasoned adjustment.
Bringing the Skills Together Continued
That kind of answer is strongest when every action is attached to its practical reason.
In practical answers, link the action to the reason. "Repeat the trial" gains more credit when it is connected to controlling a variable, improving comparability, reducing risk, or following the stated method.
Explain It Back
Use this as a self-explanation check after the section above. It is for diagnosing what you can already explain, not for learning new material from scratch.