Applied Science: F185 Forensic biology unpacked
21 September 2026
Andri Achilleos, Science Subject Advisor
As we move into the second year of the Cambridge Advanced National in Applied Science, year 13 students will begin or continue their first optional NEA unit.
We know teachers of optional unit F185, Forensic biology, can sometimes find it challenging to balance practical work, assessment requirements and developing students’ skills. In this blog I’ll highlight key teaching approaches, from planning to implementing the NEA, along with sharing useful resources and answers to the most common questions we have been asked in the past year.
Planning for delivery
Start with the specification and scheme of work
The best place to start is Teach Cambridge. Our detailed scheme of work for F185 provides delivery ideas and our Subject knowledge support sections at the end of topics are very useful for non-specialists and early-career teachers.
Make use of independent learning
If lesson time is limited, the student independent learning column can help students prepare before the lessons and reinforce learning afterwards.
ExamBuilder
Students often arrive with different levels of practical experience. You could use ExamBuilder to build quick baseline assessments to see what your students already know and where to focus attention in lesson time. Remember that F185 has a synoptic assessment of understanding and skills from Unit F180 – cell, structure and microscopy, and F181 – communicating science and handling scientific data. You can draw from questions across GCSE, Cambridge Technicals and Cambridge Advanced Nationals.
Assessment materials and professional development
The candidate style work, moderators’ reports and the set assignments are all available only to teachers through Teach Cambridge. Look out for the common issues students have with accessing command words, expectations around level of detail in responses and how to maximise marks. A list of command words and definitions can be found in Appendix B of the specification and could be useful to students.
Join us on our professional development events online, especially Ask the Moderator and Enhancing your Teaching: Supporting you to deliver investigative skills. Our teacher networks are also a great way to swap ideas and get support.
Choose the most appropriate assignment for your cohort
Set assignment B is valid for assessment from September 2026 to June 2028. Centres with students entering year 13 in September have flexibility and may choose to use either Assignment A or Assignment B. Many centres may prefer to use Assignment B with their year 13 cohort, as this also permits the opportunity for resubmission if required.
Understanding the assessment conditions
Teachers often ask if the assessment needs to be carried out under exam conditions. Unlike a written exam, the assessment must be completed under supervision, but students can still refer to their notes and research materials throughout the assignment.
Other useful resources
Forensic Biology School could be a useful way to introduce students to the idea of crime scene investigation before they begin their own practical work. This virtual environment supports students to collect evidence from a greenhouse robbery without contaminating the scene. They can then analyse samples in a crime laboratory using techniques such as soil culture and DNA analysis, quickly and without mess. The site also includes teacher support materials, including a PowerPoint and videos, which will help you guide students through the activity and link it to the skills developed in Unit F185.
Topic area 2 also introduces the use of a stereo microscope, which may be less familiar to students than a light microscope or electron microscope. If you would like to explore this further in teaching, the stereo microscope in forensic applications gives examples of how stereo microscopes can be used in forensic contexts. Where a stereo microscope is not available, a handheld magnifying glass could still help students practise observing evidence carefully while keeping the crime scene intact.
Preparing students for the assignment
Help students plan before they test
Students often want to carry out every test available. Encourage them to think carefully about which tests are needed and in what order. Using decision trees during teaching can help students develop a logical approach and select appropriate tests rather than unnecessary ones.
Practise writing assessment-style responses
Use the sample assessment material (SAM) regularly throughout the course. Peer assessment and class discussion of responses can help students understand command words and what different marking criteria actually require. Provide students with the definition of each command word (Appendix B of the specification).
Develop good organisation habits
Students should complete the assignment in a single document and in task order. Adding page numbers from the start makes it much easier for both teachers and moderators to track evidence and awarded marks.
Students should also become confident with referencing before the assessment begins. Encourage them to use the same referencing method consistently throughout the course, including when using class notes.
Build practical confidence early
Several aspects of the assignment benefit from practice during teaching:
- writing detailed risk assessments
- distinguishing between hazards and risks
- photographing and annotating qualitative results
- recording observations appropriately
- presenting data using correct units and significant figures/decimal places.
The more familiar these skills are before the assignment starts, the more students can focus on applying them independently.
Focus on the level of detail needed
Students often underestimate how much detail is required when planning methods.
They should specify:
- all equipment needed
- quantities and concentrations of reagents
- sizes of apparatus where relevant
- enough detail for another person to follow the method successfully
Activities that highlight the importance of precise instructions can help students understand the expected standard.
Implementing the assessment
Reviewing student plans before practical work begins
Review each student’s proposed methods and risk assessment before practical work starts. Make sure:
- requested equipment is available
- procedures are safe
- students can carry out the work independently.
Building time into the schedule for these checks can prevent problems later.
Setting up the ‘crime scene’ for investigation
Students must collect evidence independently (so you cannot have two students collecting samples at the same time from the same ‘crime scene’). To make this manageable with a large cohort, you may want to set up multiple crime scenes within the same room and allocate one to each student. You must provide photographs of the ‘scene’ in advance to support them in completing their own planning. Technicians can reset scenes between sessions.
Making effective use of technician support
Students are expected to independently plan how they will collect and analyse evidence and must carry out the collection themselves. The technicians will prepare and provide the samples for the suspects. Technicians are responsible for “Collecting and preserving” the suspect samples, while the crime scene evidence must be collected directly by students as part of their investigation. There is flexibility in how the suspect samples are sourced. Centres may choose materials that are practical and safe to use in a school setting. For example, animal blood may be used; there is no requirement to use human biological material.
Selecting appropriate analytical techniques
Students should select appropriate techniques based on the scenario and the evidence available. Teachers can make students aware of the equipment and resources available, but students should make their own decisions about which methods to use. There is no single prescribed approach to analysing the evidence.
If you are looking for additional practical activities, the Practical Activity Groups from A Level Biology may provide useful ideas. For example, PAG 1 is focused on microscopy and PAG 7 is focused on microbiological techniques.
Selecting an appropriate number of forensic tests
There is no minimum number of forensic tests that the student must carry out. Students should carry out enough testing to support valid conclusions and meet the assessment criteria. Students would need to carry out enough forensic tests to be able to give a good conclusion (and achieve all the latter criteria).
It’s best to share the criteria in advance with students so they can factor this into their planning. They may not need to observe and analyse everything they have recovered, but they will need to be able to account for what they have and have not decided to observe and analyse. This can be useful when discussing limitations.
Moderation and administration
What evidence do moderators need to see?
To support moderation, centres should:
- annotate work clearly
- identify where criteria have been met
- use the Unit Recording Sheet (URS)
record criteria as awarded, not awarded or not attempted.
Can Cambridge OCR review student work before moderation?
No. However, candidate exemplars, moderators' reports and other support materials are available through Teach Cambridge to help centres interpret the assessment criteria.
Other FAQs
Can students have the assignment from the start of the course?
Yes.
Do students have to complete the work within the guided learning hours?
No. The guided learning hours are intended to support planning. Students can be given additional time if needed and centres do not need approval from Cambridge OCR to do this.
Can teachers intervene if students get stuck?
Yes. The compensation model allows teachers to intervene when necessary to help students continue with the assignment. Any support provided should be recorded clearly and reflected in assessment decisions.
Is DNA analysis required?
No. DNA extraction and analysis can be used where facilities are available, but they are not required. There is no single prescribed method for analysis. Techniques such as DNA extraction and gel electrophoresis are optional and may be used if facilities allow. Where this is not feasible, students should learn about alternative approaches, such as:
- Culturing “saliva” samples to compare oral microbiomes
- Other appropriate comparative biological techniques
The equipment list is intentionally broad so centres can choose practical approaches that suit their budgets and match their own risk assessments.
Do students need to prepare all samples themselves?
No. Students may work with samples or slides they have prepared themselves or with materials provided by the centre. However, they must independently collect, preserve, package, label and store evidence from the ‘crime scene’, and clearly state the origin of any samples used. In the awarding of P8, the set assignment doesn’t require students to personally prepare every sample or slide. Task 2 requires students to preserve, record, collect, package, label and store evidence from the ‘crime scene’. Task 3 then requires them to select and perform appropriate analytical techniques on the evidence obtained from the crime scene and the evidence collected from ‘the suspects’.
They might:
- prepare, observe and analyse their own slides
- observe and analyse pre-prepared blood smears
- perform presumptive blood tests and observations/analysis.
It is important to remember that students should independently decide how to collect and compare the samples they recover from the crime scene with those available from ‘the suspects’. They should declare in their work the origin of any samples (i.e. whether they prepared them or they were provided by ‘the police’) and this will support their evaluations later on. If slides are pre-prepared this doesn’t replace the need to recover all of the evidence from the scene themselves, in accordance with their plan.
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About the author
Andri was a teacher for ten years before joining Cambridge OCR in January 2019 as the subject advisor for A Level Biology. She studied Biology at University of Bristol and completed an MA in Science Education at University of York. She has taught in Birmingham as Teacher in charge of Biology, as well as an international school in Europe. During her teaching career she has taken on various roles within the department and has also been an examiner for different exam boards.
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