OCR AAQ Applied Science • F185 • Lesson 10 • Task 1 preparation

Planning the Analysis: Evidence → Test → Result → Limitation

Build a defensible analytical plan using the smallest useful toolkit — not every forensic technique you have ever heard of.

📖 Stereomicroscope in forensics▶ Scanning electron microscope (5 min, wider tool)▶ How to use a light microscope (13 min)
By the end

You should be able to…

  • select an appropriate analytical technique for common Task-1-relevant evidence
  • write a step-by-step method including equipment, quantities, PPE and repeats where appropriate
  • state what result format will be produced
  • explain why a chosen technique is appropriate and identify a limitation
What is wrong with writing “use a microscope” as an analysis plan?
Integration lesson

The small analytical toolkit you actually need

Click each information panel. It opens straight to the information — no extra reveal.

🔬Light microscopySmall prepared specimens such as hair/fibres/cells.Click for information
👀Stereo microscopySurface detail on larger trace evidence.Click for information
📏Visual / metric comparisonPrints, teeth marks, paint layers and other features.Click for information
🧫Microbial comparisonCultured-soil colony morphology under safe procedures.Click for information
Professional labs use much more: electron microscopy, DNA profiling, PCR, gel electrophoresis and other advanced techniques. For Task 1, choose a method because it answers the evidence question and is supported by the centre's evidence/equipment.
Method quality

A Task 1 analytical method must be workable

Equipment

Specify what is needed, including sizes/quantities where relevant.

Steps

Use a logical sequence another person could follow.

Safety / PPE

Include controls appropriate to the evidence and procedure.

Repeats + results

State repeats/comparisons and how observations will be recorded.

Which is better: “compare the fibres” or a reproducible method?
Teacher model

Upgrade a vague method

Weak: “Look at the questioned fibre under a microscope and compare it with the suspects.”

Turn it into a method someone could actually follow.

Where should the scientific justification go?
Guided practice

Choose the analytical route

Press start

Work through the cases one at a time.

These are parallel practice examples, not the live set assignment.

Independent consolidation

The Equipment Store Theft – Mini Analysis Plan

A parallel practice case supplies a questioned blue fibre with three reference fibres; a questioned shoeprint with three references; a questioned soil culture with three references; and a photographed teeth mark with reference impressions.

Choose two evidence types and write: technique, step-by-step method, equipment/quantities, PPE, repeats, results format, justification and one limitation.

Review notes

  • Technique selection must follow the evidence and scientific question.
  • Light and stereo microscopes have different strengths; electron microscopy is not automatically necessary.
  • Questioned-reference analysis should use the same features/measurements for every sample.
  • Task 1 P3 methods need equipment sizes/quantities where relevant, logical steps, PPE, repeats and a results plan.
  • M2 explains why the chosen method is scientifically appropriate; it is not simply a duplicate of P3.
  • Every method has limitations and conclusions should remain proportional to the technique.

Glossary

Why this matters for Task 1

This lesson directly rehearses P3: create a step-by-step analysis plan, and M2: explain why the chosen analytical methods are appropriate.

Final checkpoint

Lesson 10 quiz