Whose Blood, Whose DNA

Read me first: how this handout is organized

Complete one serology worksheet: Parts A–E plus your case's late-record log. Use your class's supplied illustrative records. Your work explains a classroom comparison and a reported collection plan; it does not claim that you collected or tested a sample.

1. Part 1. Background and definitions. Six short readings and the terms. Read R1 to R4 before you write, and R5 and R6 when a task sends you there.
2. Part 2. Directions in plain English. Five steps, one per part of the worksheet, and the 80-minute plan.
3. Part 3. Worked example. The F1 workflow and Sample P, a comparison done once on a practice sample that is not your case.
4. Part 4. Your work. Your Case B observations, references and collection plan, then the response sheet for Parts A to E, then the late-record page for the final ten minutes.

Start with Part 1, then follow the steps in Part 2. Everything you write goes in the one worksheet in Part 4.

Supplied illustrative case record, available to all students. The source supplies reference summaries, not newly inspected original reference cards. A label other than a type does not supply the exact alternative type. Do not invent it.

Your Case B D09 assignment · Daily directions on the portal

Part 1. Reading R1 and R2

Why today matters: Two records can match on a shared feature without identifying a person. What must your worksheet show so another reader can see that limit?

Everything in your worksheet comes from these six readings. A1 uses R2 and A2 uses R1 and R3. B1 uses R2 and R3. B2 uses R3. B3 uses R5. C1 uses R4. D1 uses R2 and R6. E1 to E3 check R2, R3 and R4.

R1. Your one worksheet

Complete the serology worksheet, Parts A–E and your case's late-record log. Serology is the study of blood and other body fluids. Use the supplied illustrative records for your class's case. You are interpreting these records, not reporting tests or collection work you performed. Yesterday's screening classification does not establish a confirmed material identity. No DNA profile is supplied today.

Keep each evidence ID beside its observations and comparison. The reference summaries are supplied records, not reference cards you independently inspected. A record may give less information than you would like. Preserve that limit instead of filling the gap.

R2. The ABO typing rule

An antigen is a marker an antibody can bind. Here, A and B antigens are markers on red blood cells. An antibody is a protein that binds a particular target. Agglutination means visible cell clumping caused by antibody binding. In this classroom model, anti-A serum contains antibodies to A markers; anti-B serum contains antibodies to B markers. These are the model's testing liquids, not the person's blood-type name.

The table above is the ABO typing rule. Use it only to interpret the supplied model. It does not validate a real blood-typing test. Type O means neither A nor B marker under the ABO typing rule, not that a red blood cell has no markers at all. NCBI ABO background [S1].

Part 1. Reading R3 and R4

R3. Compare one feature and state its limit

ABO types are shared by many people. A matching type does not identify a donor. Compare the stain's classroom call with each supplied reference. The same call means they match on this one feature. A different call means they do not match under the ABO typing rule. Neither statement establishes where a person was, when material arrived, innocence or guilt.

If a reference says only other than B or other than O, keep those words. The exact alternative type is not supplied. A categorical summary can support a same/different comparison without supplying a more precise type.

DNA results can support a comparison with a reference, but conclusions depend on the actual results and their limits. No DNA profile is supplied for this worksheet, so do not make a DNA identification. NIJ comparison-result background [S2].

R4. Explain the reported collection plan

Moisture and storage conditions can affect how well biological evidence is preserved. Packaging requirements depend on the material and the approved procedure. For this paper exercise, describe the packaging and custody steps reported in your case. Do not say you performed them. Custody means the record of who handled an item. Use the collector and receiver roles, and mark unreported names or times not reported. The reported paper-envelope state is case information, not a universal packaging instruction. NIJ preservation background [S3].

Attached follicular tissue may provide DNA for testing. Follicular tissue is tissue from around a growing hair. Hairs without attached tissue can also contain DNA, but useful results depend on the sample and method. Appearance alone does not provide a DNA result. Record the tissue condition and plan stated in your own case; do not claim you inspected a specimen or established test success. NIJ-supported rootless-hair research [S4].

Part 1. Reading R5 and R6

R5. Keep practice arithmetic separate

A reference range is a stated comparison interval. Keep its label and context attached. For the separate practice numbers, compare the given value with the lower and upper limits. To find points above the upper limit, subtract that upper limit from the value. To find percent of the upper limit, divide the value by the upper limit and multiply by 100.

Percent of the upper limit = practice value ÷ upper limit × 100.

This differs from percent above the upper limit. Use the requested label. The practice values have no supplied measurement unit, so do not add mg/dL. Sample P's 150 example and your 180 calculation are separate from the case's late record. The calculation does not diagnose a person.

R6. Record the late information, without a clinical conclusion

A useful log keeps the sample ID, record label, units when supplied and relevant context. Some results are numbers; others are categories. Toxicology is the study of drugs and poisons. A glucose meter memory or a food-test category does not become a complete toxicology or cause-of-death conclusion.

Your case's late record is used in the final ten minutes. Follow only the matching case note below.

PLTW connection and preparation

This John Hay original worksheet practices model comparisons, careful record keeping and evidence limits connected to PLTW Activities 1.1.4 Blood Evidence and 1.1.5 DNA Evidence. It does not certify official activity completion. The complete required explanation is here; background links are support, not extra assignments.

Optional help

F1 shows the paper-record workflow. The separate Sample P example models a comparison, and its 150 example models the arithmetic. Guided notes can support your work but are not another submission. Before any separate teacher-directed physical collection, complete the existing preparation requirement and use the approved instructions. This worksheet does not grant a practical pass. Carry your record to the next assigned case lesson, without assuming that it already has a DNA or clinical result.

Part 1. Plain-English terms and the limit

Part D asks you to use two of these correctly: agglutination and toxicology.

Serology

The study of blood and other body fluids.

Supplied illustrative case record

You are interpreting these records, not reporting tests or collection work you performed.

Antigen

A marker an antibody can bind. Here, A and B antigens are markers on red blood cells.

Antibody

A protein that binds a particular target.

Agglutination

Visible cell clumping caused by antibody binding.

Anti-A and anti-B serum

In this classroom model, anti-A serum contains antibodies to A markers; anti-B serum contains antibodies to B markers. These are the model's testing liquids, not the person's blood-type name.

Classroom ABO call

The type the ABO typing rule (the R2 table) gives from two supplied observations. Use it only to interpret the supplied model. It does not validate a real blood-typing test. Type O means neither A nor B marker under the ABO typing rule, not that a red blood cell has no markers at all.

Other than B or other than O

If a reference says only other than B or other than O, keep those words. The exact alternative type is not supplied.

Same call and different call

The same call means they match on this one feature. A different call means they do not match under the ABO typing rule. Neither statement establishes where a person was, when material arrived, innocence or guilt.

Custody

The record of who handled an item. Use the collector and receiver roles, and mark unreported names or times not reported.

Follicular tissue

Tissue from around a growing hair. Hairs without attached tissue can also contain DNA, but useful results depend on the sample and method.

Reference range

A stated comparison interval. Keep its label and context attached.

Percent of the upper limit

Practice value ÷ upper limit × 100. This differs from percent above the upper limit.

Toxicology

The study of drugs and poisons. A glucose meter memory or a food-test category does not become a complete toxicology or cause-of-death conclusion.

The limit that applies to everything today

A matching type does not identify a donor. No DNA profile is supplied for this worksheet, so do not make a DNA identification. The finished worksheet does not claim a test, collection, DNA identity or clinical conclusion.

Before any separate teacher-directed actual collection, complete the existing DNA Evidence from the Scene preparation requirement and use the approved instructions. The paper worksheet does not certify that practical work.

Part 2. Directions in plain English

Use supplied classroom typing observations to make limited comparisons, explain a reported collection plan and accurately log a case-specific late record.

You fill in one worksheet with five parts, A to E, plus the late-record log in the final ten minutes. The five steps below match that order. Each step says what to do, what to use and where to find it.

1. Start in Part 1. Put your period and investigator code on the worksheet and label it supplied illustrative case record. Read R1 to R4, then answer Part A. A1 uses the ABO typing rule in R2, and you copy the first three words of the sentence you used. A2 uses R1 and R3.
2. Read the worked example in Part 3 before your own case. Sample P shows one type call made from two supplied observations, and two comparisons written with their limits, on a practice sample that is not your case. Then go to Part 4 and complete B1: fill in the model type call for each observation row from its supplied anti-A and anti-B results, then compare each of your two stain calls with all five reference summaries. Keep every evidence ID, and keep an other-than category when that is all the record gives.
3. Still in Part 4, write B2 and C1. B2 is a hypothetical, two sentences on what a same-type match agrees on and what it does not establish. C1 is a four-to-six-sentence explanation of one swab entry from your case's reported collection plan, using R4 for the preservation reason and the reported custody roles. Write not reported where a name or time is missing, and never invent a signature.
4. Finish the practice calculation and the checks: B3, the 180 practice value shown with the subtraction and 180 ÷ 99 × 100 and labeled percent of the upper limit; D1, one or two sentences using agglutination and toxicology; and E1 to E3. The 180 value and the B and O hypothetical are practice, not case evidence. Check that all ten task IDs are complete.
5. In the final ten minutes, log your case's late record on the last page of the worksheet, copying exactly what the record supplies and stating what it does not, then hand in the one worksheet on paper or as one PDF to your section assignment.

The 80-minute plan is on the portal page and the slides.

The model and these checks do not require another upload. Complete Parts A–E and your late-record log in the one serology worksheet.

Before you submit

Your worksheet needs the model calls from the supplied observation rows, comparisons for both stain IDs, B2's two sentences, B3's calculations, C1's plan explanation, D1 and E1–E3, plus the correct late-record log. No unreported exact reference type, time, unit, signature or clinical conclusion should be added.

Hand the paper worksheet to Mr. Mendoza before leaving, or submit one PDF in Wk4 D09 · Whose Blood, Whose DNA (PLTW 1.1.4) by September 18 at 11:59 PM. Use your period and investigator code. Do not submit the same worksheet twice. Keep notebook pages in your notebook.

If you were absent or need help

Use the same supplied-record handout and complete the same product. Its late-record section is included; work on that section after Parts A–E. You do not need to collect a new specimen or invent a missing observation. If your teacher separately assigns actual collection, follow the applicable preparation and approved instructions. This paper worksheet does not complete that practical requirement.

Lost your place? Find the next unanswered task ID and use F1's restart cue. Guided notes and the separate worked model are support, not extra submissions.

If your teacher is absent: Complete the supplied paper-record worksheet using the required briefing and models. Do not begin unassigned physical collection. Use the late-record section after Parts A–E.

Part 3. Sample P: separate practice, not your case

Sample P is a training-kit sample, not evidence in either case. Read it for the order of the work, because B1 asks for the same order with your own rows: read the two supplied observations, apply the ABO typing rule (R2), compare with each reference, state the limit.

This worked model uses the existing training-kit Sample P and two practice reference labels. It is not evidence for Case A or Case B. Use the structure, not these labels or answers, in your worksheet.

Read the supplied observations

The Sample P record describes grainy liquid with small dark clumps in the anti-A well, and smooth, even liquid in the anti-B well. In the supplied record that is anti-A yes, anti-B no. This is text describing the practice wells, not an image you personally examined or a test you ran.

Using the ABO typing rule in R2, anti-A clumping only gives the model call A. Practice Person 1's reference card is labeled A; Practice Person 2's card is labeled O.

Model the comparison and its limit

A complete comparison statement keeps both sides visible: “Sample P and Person 1 match on the supplied classroom ABO type A. That shared type does not identify the donor.” For Person 2: “Sample P's model type A differs from Person 2's stated type O. This is a mismatch in this one comparison, not proof about a person's actions.”

Your case may give a reference only as “other than B” or “other than O.” Keep that category in your comparison. Do not invent a specific replacement type.

Part 3. Sample P: the practice arithmetic and the hypotheticals

The existing made-up practice value is 150, with a supplied comparison range of 70 to 99. No measurement unit is supplied.

1. Compare with the interval: 150 is above its upper limit of 99.
2. Find the difference: 150 − 99 = 51 points above.
3. Find percent of the upper limit: 150 ÷ 99 × 100 = about 152% of the upper limit.

The last label is “percent of,” not “percent above.” Your B3 task uses 180, not 150. Show your own calculation and keep this generic practice separate from any case reading or clinical interpretation.

A separate hypothetical check

B2 imagines a stain and a reference with the same type. It is not another observation in your case. E2 imagines a type-B stain and a type-O reference; this is practice for both sections. Apply R3's one-feature comparison limit rather than using either hypothetical to change your case rows.

The model and these checks do not require another upload. Complete Parts A–E and your late-record log in the one serology worksheet.

Part 3. F1. Read, compare, record, the workflow

Find your own-case evidence ID and both supplied clumping observations. Use the ABO typing rule in R2 to make the model type call. Compare that call with the supplied reference information. State agreement or disagreement only for this one feature. If information is missing, say so; do not fill an “other than” category with a guessed exact type. Add the comparison limit. Then finish the collection-plan explanation and separate arithmetic practice in the same worksheet. In the final ten minutes, log only your own case's late record. Preserve its display or category, source and missing context. The finished worksheet does not claim a test, collection, DNA identity or clinical conclusion.

Optional restart cue

Find the next unanswered task ID. Use R2 for the typing grid, R3 for comparisons, R4 for the collection-plan explanation, R5 for the practice calculation and R6 for the late record. Do not switch to the other case or create a second product.

Part 4. Your Case B observation rows and reference summaries

Everything from here on is yours to write. These records are the inputs for B1 and C1.

Supplied illustrative case record, available to all students. The source supplies reference summaries, not newly inspected original reference cards. A label other than a type does not supply the exact alternative type. Do not invent it.

Setting: Respawn, an e-sports lounge with a smoothie counter. Case number JH-26-0831-B.

Observation grid: 3 supplied rows, model type call left blank

All five reference summaries, used for each stain

• Victim, medical record (reference): anti-A No, anti-B No; type O reported in the case record.
• Whitfield: OTHER than O; exact type: not supplied.
• Nguyen: OTHER than O; exact type: not supplied.
• Rao: OTHER than O; exact type: not supplied.
• Boone: OTHER than O; exact type: not supplied.

Same-type stain/reference comparison is a hypothetical prompt, not an additional match in either supplied case.

Part 4. Your Case B reported collection plan and custody state

• Counter stain swab; evidence ID E2-counter.
• Floor stain swab; evidence ID E2-floor.
• straw swab from the smoothie cup; evidence ID E3.
• storeroom hair root; evidence ID: not supplied; root tissue reported available: yes; recorded plan: it goes to DNA.
• protein container lid swab; evidence ID: not supplied.

References reported on file: reference swabs already on file for the victim and all four persons of interest.

The tissue status is supplied narrative, not an independently inspected specimen or a guaranteed DNA result. The sheet does not give an exact hair/lid evidence ID here. Do not invent one or infer E4/E5 for the lid.

Reported custody state: Swab air-dried, sealed in a paper envelope (not plastic), labeled with the E-number, first custody row signed by the collector and the receiver.

Reported roles: collector and receiver. Collector identity: not reported. Receiver identity: not reported. Collection time: not reported. Transfer time: not reported. Actual signatures: not reported.

Reported illustrative packaging/custody state, not proof the student performed it or a complete approved collection protocol.

Practice numbers, not from the case

Value 180, supplied range 70 to 99, measurement unit: not supplied. Requested: inside the supplied range?; points above the upper limit; percent of the upper limit: 180 / 99 × 100.

Part 4. Response sheet, Part A: use the reading

Case B, RESPAWN, Period 6A-7B. Investigator code, not name:

Record route label: Supplied illustrative case record, available to all students.

Date: September 18, 2026

Complete the serology worksheet, Parts A–E and your case's late-record log. Serology is the study of blood and other body fluids. Use the supplied illustrative records for your class's case. You are interpreting these records, not reporting tests or collection work you performed. Yesterday's screening classification does not establish a confirmed material identity. No DNA profile is supplied today.

A1 PBS-U1-D09-A1

In one sentence, explain why clumping can occur with anti-A serum in this classroom model. Use the terms antibody and A marker. Copy the first three words of a supporting sentence in R2.

Explanation

Supporting sentence starts

A2 PBS-U1-D09-A2

Explain one limit of a same-type comparison and why today's worksheet cannot make a DNA identification.

Same-type limit

DNA-input limit

Part 4. Response sheet, B1: observation grid

B1 PBS-U1-D09-B1

Use the supplied anti-A and anti-B observations to fill the model type call for each observation row. Then compare each of your two stain calls with all five supplied reference summaries. Keep the stain ID, reference label, reported pattern or category, same/different result and limit together. Do not invent an exact type for an other-than category.

Four observation rows are supplied in A and three in B, including references with well observations. All five reference summaries are still used for each stain. Missing exact types remain categorical.

Observation grid: row label, supplied anti-A, supplied anti-B, blank model type call

Part 4. Response sheet, B1: comparison grid for E2-counter

B1 PBS-U1-D09-B1

E2-counter: Counter-edge stain. Supplied anti-A No (smooth well); supplied anti-B No (smooth well). Your model type call from the observation grid:

Comparison grid: stain ID, reference label, supplied reference pattern/category, blank same/different call, reason and limit

Part 4. Response sheet, B1: comparison grid for E2-floor

B1 PBS-U1-D09-B1

E2-floor: Floor stain. Supplied anti-A No (smooth well); supplied anti-B No (smooth well). Your model type call from the observation grid:

Comparison grid: stain ID, reference label, supplied reference pattern/category, blank same/different call, reason and limit

Part 4. Response sheet, B2 and B3: a hypothetical and practice numbers

B2 PBS-U1-D09-B2

Hypothetical practice, not a new case result: a stain and a person-of-interest reference have the same classroom ABO type. In two sentences, state what agrees and what that agreement does not establish.

Do not add this hypothetical match to your case matrix.

Two-sentence comparison and limit

B3 PBS-U1-D09-B3

Practice numbers, not from the case: a value is 180 and the supplied range is 70 to 99. Is it inside that interval? How many points above the upper limit is it? What percent of the upper limit is 180? Show the subtraction and 180 ÷ 99 × 100. Label percent of the upper limit, not percent above. No measurement unit is supplied.

Use 99 as the upper limit for this practice. Do not use the case reference card or add mg/dL.

Inside/outside

Difference calculation

Percent-of-upper-limit calculation and label

Part 4. Response sheet, Part C: the reported collection plan

C1 PBS-U1-D09-C1

Choose one swab entry from your case's supplied collection-plan record. In four to six sentences, explain the reported item and location; its reported packaging and the preservation reason from R4; the collector/receiver roles and any unreported names or times; and the reference samples reported on file. This is a paper-record explanation, not instructions for performing collection or a claim that you packaged the sample.

Do not invent an evidence ID for a lid or hair entry whose ID is not supplied, and do not write an actual signature. Use a listed swab entry for this response.

Chosen source label and existing evidence ID if supplied

Four-to-six-sentence explanation covering the four components

Part 4. Response sheet, Parts D and E: vocabulary, then practice checks

D1 PBS-U1-D09-D1

Use agglutination and toxicology in one or two sentences about this worksheet. Explain their roles without treating the late record as a diagnosis or a complete toxicology conclusion.

The typing model and the study of drugs/poisons are different concepts. Do not invent a toxicology result.

One or two applied sentences

E1 PBS-U1-D09-E1

Practice check: the supplied observation says clumping with anti-A only. What is the classroom model call?

This is a check of the ABO typing rule, not another assigned stain.

Model type call

E2 PBS-U1-D09-E2

Hypothetical practice for both cases: a stain has classroom type B and a reference has type O. Write the same/different comparison and one limit. Do not change your case records.

Limit the statement to this feature comparison, not a person's actions.

Comparison and limit

E3 PBS-U1-D09-E3

Why can moisture matter when preserving biological evidence? State the reason from R4 and keep real packaging decisions tied to the material and approved procedure.

Do not claim that one package is suitable for every specimen or that you performed the reported steps.

Preservation reason and limit

Your worksheet needs the model calls from the supplied observation rows, comparisons for both stain IDs, B2's two sentences, B3's calculations, C1's plan explanation, D1 and E1–E3, plus the correct late-record log. No unreported exact reference type, time, unit, signature or clinical conclusion should be added.

Optional single comparison check, not alternate work plans

A reference is labeled only other than B. What should the worksheet preserve?

1. Choose a likely exact alternative type.
2. Keep other than B and make only the supported classroom comparison.
3. Use Sample P's reference type in its place.

The model and these checks do not require another upload. Complete Parts A–E and your late-record log in the one serology worksheet.

Notebook support, not another submission

Keep notebook pages in your notebook.

Optional support

• Optional Guided Notes
• Separate Sample P and 150 worked models
• Existing voluntary vocabulary extra credit, kept separate from required D1

Turn in, PLTW and sources

Complete one serology worksheet, Parts A–E plus your case's late-record log. Hand the paper worksheet to Mr. Mendoza before leaving, or submit one PDF to this section's assignment by September 18 at 11:59 PM. Use your period and investigator code. Do not submit twice; keep notebook pages in your notebook.

Keep today's worksheet for the next assigned case lesson. Later evidence must be supplied before you use it; do not assume a DNA or clinical result already exists.

This John Hay original worksheet practices model comparisons, careful record keeping and evidence limits connected to PLTW Activities 1.1.4 Blood Evidence and 1.1.5 DNA Evidence. It does not certify official activity completion.

John Hay original local work connected by title; no official completion claim. The complete required explanation is here; background links are support, not extra assignments.

Case B D09 assignment · Official PLTW section hub · Activity 1.1.4 Blood Evidence · Activity 1.1.5 DNA Evidence

Sources and optional background

• S1. NCBI ABO background

  cited in R2.

• S2. NIJ comparison-result background

  cited in R3.

• S3. NIJ preservation background

  cited in R4.

• S4. NIJ-supported rootless-hair research

  cited in R4.

• S5. FDA display explanation

  cited in R6.

• S6. FDA fasting-context explanation

  cited in R6.

• S7. Antibody-binding background

  cited in R6.

A matching type does not identify a donor. No DNA profile is supplied for this worksheet, so do not make a DNA identification. The finished worksheet does not claim a test, collection, DNA identity or clinical conclusion.