PBS/PBT · September 15 · D07 · Case A STATIC · Period 1-2
MODEL-1: read a fingerprint comparison record
Separate supplied classroom practice, not Case A or Case B and not another assignment.
Start: Read the model, then return to your own-case sheet. Digital deadline: September 15, 11:59 p.m.
MODEL-1: separate locker-print practice
These are supplied counts, not an image you recounted. The model is not Case A or B. Its pattern is a right loop, with 16 readable minutiae. Card 1 has 13 matching and 0 mismatching. Card 2 has 5 matching and 3 mismatching.
- List the features before considering the card's identity: right loop and 16 readable ridge details. A pattern family is a class feature.
- Compare card 1's supplied count with the classroom rule: 13 is at least 12, and the record reports zero mismatches. Under this exercise model, this supports the model's “individual” call, consistent with card 1. It is not automatic proof of identity or an action.
- Compare card 2's supplied count with the same model. The record includes three mismatches. Under this simplified classroom rule, the comparison is inconsistent with card 2. This is an exercise conclusion, not a real forensic exclusion based only on counts.
- Show the card 1 proportion: 13 ÷ 16 × 100 = 81.25%, or about 81% to the nearest whole percent. This percentage describes matching features in the record, not the probability that card 1's source touched the locker.
- Keep the limit beside the comparison. A match in this classroom comparison supports a possible source under the exercise rule; it does not by itself prove who touched the object, when, or why.
Finished practice entry and counterfactual
MODEL-1 reports a right loop with 16 readable minutiae. Card 1 has 13 matches and zero mismatches, meeting the classroom model's rule; 13 of 16 is about 81%. Card 2 has five matches and three mismatches, giving an inconsistent comparison under that same model. These practice counts support bounded comparisons, not proof of who touched the locker or when.
The original model also asks you to imagine nine of 16 matching details with zero mismatches. That gives 56.25%, about 56%, and is below the classroom model's 12-match requirement. This counterfactual is practice only. Do not copy its numbers into B3, which supplies its own values.
Begin with the evidence number and source label. Copy the reported features. Check whether the necessary comparison information is actually present. Use the supplied counts or approved reference features only. End with a conclusion no stronger than those inputs support.
Known-hair reference features are not supplied. Record the reported features and the missing comparison input. Do not name a matching or excluded source. A missing reference is not a mismatch or evidence of absence.
Connection to PLTW
Related PLTW reference:
- Activity 1.1.3 The Traces We Leave Behind
In Lesson 1.1, Investigating the Scene. This John Hay classroom adaptation practices describing evidence, comparing available information and explaining limits.
This sheet does not replace or certify completion of the official activity. If assigned, open the matching activity through your existing myPLTW account or section hub.
Open your official PLTW section hubTurn in one sheet
Complete your D07 trace comparison sheet during class. Hand the paper sheet to me before leaving, or submit one PDF to this Schoology assignment by Tuesday, September 15, at 11:59 p.m. Submit once. Keep notebook pages in your notebook.
Turn in only the completed Parts A–E sheet. No extra CER, tracker, specimen image, microscope drawing or notebook upload is required.
Case A: submit to the D07 assignmentKeep your source-labeled comparison and its limits for the next class on Thursday, September 17. Your notebook pages stay in your notebook.
Sources and optional background
The required explanation is supplied above. These links do not add an assignment.
- S1. FBI Handbook of Forensic Services
limits of hair comparison.
- S2. NIST: follicular tag
attached follicular tissue.
- S3. NIJ-supported research on rootless hair DNA
why appearance alone cannot decide DNA-test usefulness.
- S4. Department of Justice: latent print testimony and reporting
limits on source conclusions.
- S5. NIJ Fingerprint Sourcebook
fingerprint comparison background. The numerical classroom rule above is a teaching model.
These supplied records cannot establish a hair source without known-reference features, or prove who touched an object, when or why. The 12-match rule is a classroom model, not a real forensic identification standard. No DNA result is supplied.