Analyze trace evidence
Analyze your trace-evidence observations with a CER and evaluate documentation limitations.
CER arguing what the trace evidence suggests about the scene, using Wednesday's microscopy observations as evidence and acknowledging at least one limitation.
- 1Do thisAnalyze your trace-evidence observations with a CER and evaluate documentation limitations.
- 2Use this resource
- 3Submit thisCER: CER arguing what the trace evidence suggests about the scene, using Wednesday's microscopy observations as evidence and acknowledging at least one limitation.
- 4Submit it here
- 1CMSD website. Go to clevelandmetroschools.org and click the Clever button.
- 2Clever. Clever opens. Sign in if it asks.
- 3Microsoft (district) login. Use your district Microsoft account (the one for school).
- 4Schoology. Open Schoology, then your class, then Assignments, and find the file named below.
The file to submit is named: Principles of Biomedical Technology (Principles of Biomedical Science) › Unit 1.1 Investigating the Scene: Forensic scene documentation, evidence log, crime-scene sketch, trace evidence, biometric data. › CEROpen Schoology
Read to prepare for today
Vetted sources picked for today's question. Skim these before you take a position or start the work, so your argument and evidence are grounded.
- CER:
- Claim, Evidence, Reasoning — make a claim, back it with evidence, explain your reasoning.
- SOP:
- Standard Operating Procedure — the exact steps to follow (especially in a lab).
- Tracker:
- Your PLTW progress log where you record completed evidence.
- myPLTW:
- The PLTW course site where you do the online activities — you open it through Schoology.
Minute-by-minute · 80-minute block
💡 Big idea: Observations only become evidence when you compare them against a reference and acknowledge what they cannot prove.
- 0:00Return Wednesday scene packets; review the chain-of-custody log together
- 0:10Reference comparison: project reference fiber and hair characteristics; students compare their sketches
- 0:28CER writing: claim about what the trace evidence suggests, evidence from observations, reasoning from comparison
- 0:50Chain-of-custody audit: students check their own log for missing fields; flag gaps
- 1:02List two variables that could change interpretation; state one limitation of trace evidence alone
- 1:10Pair-share CERs; preview Friday submission
- • You collected trace evidence yesterday. Now comes the harder question: what does it actually mean? A fiber is not evidence of anything by itself until you compare it to something else.
- • Today you will use reference images to compare your trace observations. If your fiber matches the reference for a known sample, that is meaningful. If it does not, that is also meaningful.
- • Then you will audit your own chain-of-custody log. Could a defense attorney find a gap? An unsigned field? A time that is out of sequence? If yes, the evidence might not make it to court.
- • Finally, you will write a CER. This is your scientific argument: here is what I observed, here is why it matters, and here is what it cannot prove.
- 1Compare your trace-evidence descriptions to reference characteristics.
- 2Write a CER: what does this trace evidence suggest about the scene?
- 3Evaluate whether your chain-of-custody log would hold up to scrutiny.
- 4List two variables that could change trace-evidence interpretation.
- 5State one limitation of trace evidence as a sole source of proof.
- • I can write a CER from trace-evidence observations.
- • I can identify limitations in evidence interpretation.
- • Trace evidence must be compared to reference standards (known samples) to have meaning; an observation alone is not identification.
- • Two key variables that affect trace-evidence interpretation are the condition of the sample (degraded vs. intact) and the analyst's reference library.
- • Trace evidence rarely proves guilt alone; it corroborates other evidence in a convergent chain.
Your PLTW work today
Unit 1.1 Investigating the Scene: Forensic scene documentation, evidence log, crime-scene sketch, trace evidence, biometric data. · Analyze trace evidence
Day 4 of this lesson. Open this exact section in myPLTW (reached through Schoology), then do the work below.
Do this: In myPLTW, complete the Lesson 1.1 Investigating the Scene analysis reflection section.
Mark the Lesson 1.1 scene-analysis reflection complete in myPLTW.
You built the scene packet Wednesday. By the end of today your CER and chain-of-custody audit should both be finished.
Completed CER (written or typed) and annotated chain-of-custody log with any gaps flagged.
All PLTW activities are completed inside the PLTW course environment — this page only gives direction. Submit producibles on Schoology.
Today's PLTW tracker
Check things off as you work, then submit. This tells Mr. Mendoza how you're doing so he can help the class. It does not replace turning in your producible on Schoology.
Use the code Mr. Mendoza gave you, not your name. Saved on this device.
Unit 1.1 Investigating the Scene: Forensic scene documentation, evidence log, crime-scene sketch, trace evidence, biometric data. · Analyze trace evidence
In myPLTW, complete the Lesson 1.1 Investigating the Scene analysis reflection section.
You built the scene packet Wednesday. By the end of today your CER and chain-of-custody audit should both be finished.
This is how Mr. Mendoza sees the class keeping pace with PLTW. Be honest, it only helps if it is accurate.
🎯 Analyze your trace-evidence observations with a CER and evaluate documentation limitations.
- Compare your trace-evidence descriptions to reference characteristics.
- Write a CER: what does this trace evidence suggest about the scene?
- Evaluate whether your chain-of-custody log would hold up to scrutiny.
- List two variables that could change trace-evidence interpretation.
- State one limitation of trace evidence as a sole source of proof.
CER: CER arguing what the trace evidence suggests about the scene, using Wednesday's microscopy observations as evidence and acknowledging at least one limitation.
Submit on SchoologyUpload by 11:29 PM for full credit.
| Task | Who |
|---|---|
| Compare your trace-evidence descriptions to reference characteristics. | _______ |
| Write a CER: what does this trace evidence suggest about the scene? | _______ |
| Evaluate whether your chain-of-custody log would hold up to scrutiny. | _______ |
| List two variables that could change trace-evidence interpretation. | _______ |
| State one limitation of trace evidence as a sole source of proof. | _______ |
Working solo? Put your own name in "Who" for every row.
- I can write a CER from trace-evidence observations.
- I can identify limitations in evidence interpretation.
Resources & readings
Hand-picked materials for this lesson. Class file items open the document directly; the rest are vetted readings and interactives from other biomedical programs.
Lab & supplies
WebXam practice
Cumulative WebXam review
A quick mixed-review pulling questions from earlier units plus today, so the WebXam material stays fresh.
Where this leads — careers
What today's skills lead to. These are real health-science careers this course builds toward. Tap one to see, on the US Department of Labor's O*NET site, what the job actually involves, what it pays, and how fast it is growing.
What to do if you were absent
Today is individual PLTW work, so do exactly what we did in class, from home: complete the same PLTW target above, then submit your CER.
Open Schoology (CMSD) and keep goingHow to get there: open the CMSD website, click Clever, sign in with your Microsoft (district) account, then open Schoology from Clever.
Class still runs. Complete the online activity above (it's self-guided). Need the concept taught without a teacher? Use this authoritative explainer:
Khan Academy: using the microscope (Cell biology)- CompleteEvery required part of the artifact is present, nothing left blank.
- AccurateThe science and the data are correct and match the evidence.
- Scientific reasoningYou explain your claim with evidence and reasoning (CER), not just an answer.
- Professional communicationClear, organized, labeled, and written the way a clinician or scientist would.
- SubmittedTurned in the right way (Schoology for routine work) and confirmed.
Drop your Thu, Sep 3, 2026 · Analyze trace evidence here. Use a clear file name (your initials + project). Routine work still goes to Schoology (via the CMSD portal).
Upload a project