⚛️ DNA & Biological Evidence — printable rubric packet (Forensic Science Unit 06). Print 8.5×11 portrait. Every page is designed for clipboard use while you grade at the bench.
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▲ Page 1 — Unit overview
Bright Minds Forensic Science · Course Pack
DNA & Biological Evidence — Unit Packet
Overview
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Use these targets, vocabulary, rubrics, examples, and score sheet with the instructor's approved lesson and procedure. This is an assessment companion, not a complete lesson or safety authorization.

Student lessons, data, and worked answers: Unit 06 learning pathway.

Unit learning targets

The student demonstrates the following:

How this unit is assessed

Mastery rubric

Five science criteria plus separately reported integration (Page 3).

Bench lab

Read a worked STR profile; make a disciplined comparison.

Oral check

The student reports a match with its random-match probability (Page 4).

Lab notebook

Profile, comparison, and match statistic kept distinct.

How to read a Bright Minds rubric

You are making a decision, not adding up points. For each criterion, decide whether the work is Developing, Proficient, or Mastery — the column language tells you which. A criterion counts as mastered only when the student can both read the profile and report the match honestly. Each student has three tokens per term; each token retries one rubric criterion. Approved accommodations, equipment failures, and approved absences are handled separately and do not consume these tokens.

▲ Page 2 — Key terms
DNA & Biological Evidence · Vocabulary
Key Terms — What Counts as Correct
Vocabulary
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Accept listed synonyms; use the distinction column to resolve near-matches.

Canonical answerAccepted synonymsCommon confusion / discriminator
Profile & method
DNA profileSTR profileA set of STR marker values; distinguishes people, is not a picture of the whole genome
STR (short tandem repeat)STR locusA region repeated a variable number of times; the count differs between people
PCR amplificationpolymerase chain reactionCopies tiny amounts of DNA so a profile can be read; amplifies, does not compare
Gel electrophoresiscapillary electrophoresisSeparates DNA fragments by size; the separation step, not the copying
Reading & reporting
Random-match probabilityRMPThe chance a random person shares the profile; a statistic, never 100%
Prosecutor's fallacytransposed conditionalConfusing “rare profile” with “probably guilty” — the error to avoid
Contamination / degradationsample compromiseForeign or broken-down DNA; limits what the profile can support
Reference / exemplar sampleknown sampleA known-source sample compared against the questioned profile
Grading it at home

The split between Proficient and Mastery is honest statistics: RMP conditions on an unrelated population model, not on guilt. Ask which loci are independent, which information is missing, and whether control or mixture problems make the simple calculation inapplicable.

▲ Page 3 — Mastery rubric
DNA & Biological Evidence · Mastery Rubric
Six Criteria — Developing / Proficient / Mastery
Rubric
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CriterionDevelopingProficientMastery
DNA structure & STR profilingConfuses bases, alleles, and loci.Describes variation but assumes every profile is unique.Explains complementary DNA and inherited STR variation using fictional loci, distinguishing a profile from a whole genome or an identity guarantee.
Extraction, PCR & electrophoresisCannot outline the conceptual process.Confuses amplification and size separation.Explains extraction, PCR, controls, and electrophoresis with paper diagrams and a size ladder, without biological sampling or wet procedures.
Reading a profile & comparisonSelects only agreeing alleles.Compares complete cards but forces a partial or mixture.Records alleles independently before comparison; distinguishes consistent, excluded, partial/mixture inconclusive, and failed-control invalid outcomes under the stated model.
Match probability & statisticsReports a probability of guilt from a match.Multiplies frequencies without checking assumptions.Calculates toy genotype frequencies and random-match probability; states population/independence assumptions, rejects duplicate-locus multiplication, and never equates RMP with guilt.
Sample integrityIgnores contamination or missing data.Notices defects but reports a firm source claim.Explains contamination, degradation, dropout, relatedness, and transfer limitations; retains failed controls and separates source association from time or activity.
Integration (cross-domain)Makes no supported connection between the source and the science.Uses the source but needs help connecting evidence, writing, or limitations to the science.Independently connects History, Reading, and Writing using a cited source, appropriate evidence, a limitation, and a scientific explanation.
What “Mastery” requires
The student retains a full fictional allele/control record and all comparison outcomes, then defends the toy genotype calculation, independence assumptions, and source/activity limits.
What does not pass
Saying “the DNA matches, so it’s a 100% match — it proves he did it” is Developing on criterion 4 — a match is a statistic, and guilt is the court's to decide.
▲ Page 4 — Anchor exemplars
DNA & Biological Evidence · Calibration
Anchor Exemplars — To Calibrate Your Ear
Anchors
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Read these before you grade. They show what Mastery and Developing actually sound like, plus the edge cases where you should coach rather than decide on the spot.

Reporting a fictional profile comparison

▶ Mastery
“Under the independent-locus model, 0.04 × 0.12 × 0.16 = 0.000768, about 1 in 1,302 unrelated profiles. B is excluded, C and M inconclusive, X invalid. The two-locus probability remains 0.0048 when a third assay only repeats L1; neither figure measures guilt.”
▶ Developing
“The DNA matches, so it’s a 100% match — it proves he did it.” (A statistic reported as certainty and as a verdict.)

Integration — sensitivity and scientific validation

▶ Mastery
“Butler’s 2021 NIST interview calls for public testing of complicated mixtures. OpenStax’s PCR and gel diagrams explain amplification and separation, not automatic interpretation. Increased sensitivity can expose mixtures or indirect transfer, not settle an activity.”
▶ Developing
“DNA catches criminals.” (No link to how profiling works or that it exonerates as well as associates.)

Edge cases — coach, don’t fail

▶ Partial profile
Over-reads a degraded, partial profile as a full match. Coach: report only the loci the sample supports; call the rest inconclusive. Fixable.
▶ Prosecutor's fallacy
Turns a one-in-a-billion statistic into “a billion-to-one he’s guilty.” Coach the difference between a profile statistic and a claim about guilt.
▲ Page 5 — Score sheet (clipboard)
DNA & Biological Evidence · Score Sheet
Unit Score Sheet — One per student
Score Sheet
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Student: ______________________________________    Date: _______________    Guide: _________________________

Mastery criteria — circle one per row

#CriterionDecisionNotes
1DNA structure & STR profilingDev / Prof / Mast
2Extraction, PCR & electrophoresisDev / Prof / Mast
3Reading a profile & comparisonDev / Prof / Mast
4Match probability & statisticsDev / Prof / Mast
5Sample integrityDev / Prof / Mast
6Integration (cross-domain)Dev / Prof / Mast

Paper-profile lab — technique check

Used a token this session?

☐ No    ☐ Yes — for criterion: __________
Tokens left this term after this session (choose one): ☐ 3   ☐ 2   ☐ 1   ☐ None left

Dev = Developing · Prof = Proficient · Mast = Mastery · Unsure between two levels? Circle the lower one and note what a re-do would need.