Collect observations safely and accurately
Follow a procedure, record objective observations and identify hazards and precautions in a supervised laboratory.
Cambridge International Biology 9700, 2028–2030. Paper 3 assesses practical skills in a supervised laboratory; these lessons support preparation but do not replace safe, supervised laboratory experience.
Before you begin
- Use biological vocabulary and basic calculations from the AS Biology course. Follow your school laboratory rules and teacher instructions for all practical work.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which statement best distinguishes a hazard from risk?
What you will learn
- Follow instructions and take readings with suitable apparatus.
- Describe qualitative observations precisely.
- Recognise hazards and use teacher-directed precautions.
Measure what the method asks
Check the instrument range and smallest scale division before reading it. Read at eye level where appropriate, keep the measurement method consistent, and record observations promptly.
For qualitative results, use clear descriptions of observable colour, shape, movement or change. “Changed” is less informative than a specific observation such as “the blue solution became colourless”.
Think about hazards and risk
A hazard can cause harm; risk considers both the likelihood and severity of harm. Identify the source of possible harm, judge its risk using the school’s method, and name a practical precaution.
Laboratory activity must follow the teacher’s instructions, school rules and local safety requirements. A written risk assessment does not replace supervision or safe handling.
Pause and explain
What makes a precaution useful?
Worked example
A practical uses a warm water bath and a biological stain. Give one hazard and a matching precaution for each.
Show the worked solution
- Consider heat and reagent exposure separately.
- State a specific action that reduces each risk.
Answer Hot water can cause burns; use the bath as directed and keep containers stable. A stain may irritate or stain skin; use the teacher-directed protective equipment and wash spills as instructed.
From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A student must measure a colour change every 30 seconds. Give two steps that improve the consistency of observations.
Give me a hint
Standardise the endpoint and reading routine.
Compare my reasoning
- Use the same lighting/background and viewing position.
- Apply the same time interval and colour description criteria.
- Record observations immediately.
Use consistent lighting and timing, define the colour scale or endpoint before starting, and record each observation at the same interval.
Look for these in your work
- Two repeatable controls
- Objective recording
A sharp glass coverslip is used to prepare a slide. Identify the hazard and one precaution.
Give me a hint
Link the possible injury to handling.
Compare my reasoning
- The glass edge can cut skin if broken or handled carelessly.
- Handle the coverslip by its edges as instructed and report breakage; follow the teacher’s disposal procedure.
Hazard: broken or sharp glass can cut. Precaution: handle the coverslip as instructed and tell the teacher about breakage so it can be cleared safely.
Look for these in your work
- Hazard stated
- Precaution directly related
An unfamiliar reagent is introduced in a practical. What should a learner do before using it?
Give me a hint
Use supplied information and supervision.
Compare my reasoning
- Read the instructions and relevant hazard information.
- Ask the teacher if the procedure or precaution is unclear.
- Use the stated controls and protective equipment.
Follow the supplied instructions and school risk assessment, check the required precautions, and ask the teacher before use if anything is unclear.
Look for these in your work
- Procedure followed
- Supervision and risk controls included
Common mistakes
- Calling something a risk without identifying a hazard.
- Suggesting vague precautions such as “be careful”.
- Changing a supervised procedure without the teacher’s approval.
What can you explain now?
Which statement best distinguishes a hazard from risk?
Compare with the explanation
A hazard can cause harm; risk considers likelihood and severity
Risk combines the chance and consequence of harm.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
How do a hazard and risk differ, and why should observations be defined before collecting data?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.