Week 5 review: the profile, the clock, and the two errors
This page has four parts, in the order you use them. Part 1 is what you need to know. Part 2 says what to do, in plain English. Part 3 shows the work done once on a case that is not yours. Part 4 is your own work and where to turn it in.
Open your materials, follow the steps, then turn in your work.
Rebuild this week's three tools from memory, then use each one on a supplied record and stop at what the evidence actually supports.
Optional: listen or watch a unit review▸
Part 1 of 4 · Background and definitions▸
💡 Big idea: Every tool this week narrows the field, and not one of them closes it.
- • An STR profile compares repeat counts at named loci. Matching repeat counts fail to exclude a person; they do not identify one.
- • Amelogenin is not an identity . It reports the sex-linked marker pattern, and it is read alongside the identity loci rather than instead of them.
- • Algor, livor and rigor mortis each move on their own approximate schedule, and each one is pushed around by temperature, body size, clothing and activity before death.
- • Three overlapping clocks give a time-of-death WINDOW. The window is the answer; a single hour is not.
- • A labels a healthy person. A releases an infected one. The two errors land on different people and cost different things.
- • A positive test reports current or past infection. It is not a diagnosis and it is not a confirmation.
A position you cannot argue against is a position you do not yet hold; you have only inherited it.
Every tool this week narrows the field, and not one of them closes it.
Driving question: You have a profile, a set of body clocks, and a test result. What can you say out loud, and what must you refuse to say?
What you already know: A position you cannot argue against is a position you do not yet hold; you have only inherited it.
New idea: Every tool this week narrows the field, and not one of them closes it.
- Observe or measure the relevant feature in today's lesson.
- Organize the observation with a stable evidence ID.
- Apply this rule: Define variables, controls, sampling, units, and the analysis plan before interpreting a result; analysis cannot repair biased or inconsistent measurement.
- Choose the option the evidence supports and state the limit of the conclusion.
Real biomedical example: A medical examiner's report gives a time-of-death range and says what it depends on, and a lab reports that a person cannot be excluded rather than naming them. Both write the finding and where it stops, because a court or a family will act on exactly what is written.
What the evidence supports: E1 to E3 and the figure support the daily take-home when the response meets the stated success criteria.
What it cannot prove: The package does not support claims beyond this lesson's or any real patient diagnosis.
- • : The body's ongoing process of keeping internal conditions like temperature, blood sugar, and pH steady despite changes in the outside environment.
- • : A group of similar cells working together to perform a shared function, such as muscle, nerve, or .
- • : A group of organs that work together to carry out a major body function, such as the digestive or circulatory system.
- • toxicology: The science of how chemicals and other substances cause harm to living things, including the dose at which they become dangerous.
- • : The study of the microscopic structure of tissues, examining thin stained slices under a microscope to see how cells are arranged.
- • : The specific physiological breakdown inside the body that directly ends life, such as a fatal heart rhythm or blood loss, separate from the underlying cause.
Use it now: Choose one decision option. Cite E1 and E3, then explain how the rule connects the evidence to your choice. This is thinking practice for the one turn-in named under Turn in, not a second submission.
Go further, optional: The source links below are optional enrichment. Every fact required for today's local evidence decision appears in this lesson package.
A planned study connects its question to defined variables, controls, sampling, measurement, and analysis so the resulting data can support a bounded and reproducible conclusion.
Limit: A statistical difference or trend does not automatically establish practical importance, causation, generalizability, or freedom from bias.
Define variables, controls, sampling, units, and the analysis plan before interpreting a result; analysis cannot repair biased or inconsistent measurement.
Limit: A well-organized classroom study can still be limited by , measurement quality, confounding, and the population represented.
You can compare STR bands lane by lane and turn each comparison into an exclusion statement.
Limit: E3 defines the classroom product or success criterion. It is not independent scientific evidence and cannot justify a clinical or causal claim.
Today's decision · Simulated classroom evidence scenario
Your role: biomedical investigator
Decision: Your team must decide what the evidence from today's lesson supports before submitting the notebook record named on today's page.
- • Name what the figure cannot tell you, then write the claim and the limit in the same breath.
- • Write the strongest claim the figure supports, and add the limit later if someone asks for it.
- • Skip the limit, because a supplied figure is evidence and supplied evidence does not need one.
Response: State one choice, cite at least two evidence IDs, explain the rule that connects them, and add one limitation. Use it inside the one turn-in named under Turn in; it is not a separate submission.
Claim ceiling: Today's evidence supports a classroom claim about today's lesson. It cannot prove causation, diagnose a real patient, or justify action outside this room.
Reason for review: Your team must decide what the evidence from today's lesson supports before submitting the notebook record named on today's page.
Context: A medical examiner's report gives a time-of-death range and says what it depends on, and a lab reports that a person cannot be excluded rather than naming them. Both write the finding and where it stops, because a court or a family will act on exactly what is written.
- • T1: Head your record: Week 5 Review Record, your period, your code, and the date.
- • T2: Part A, first: open the Case record in Part 2 of this page. Write down the three band positions of your questioned lane.
- • T3: Part A, second: compare them, band by band, with each of the three reference lanes in the Case record. For each reference write EXCLUDED or NOT EXCLUDED.
- • T4: Part A, third: under each call, write one sentence that says what the call does not prove. Use the pattern: 'This shows ___. It does not show ___.'
- • T5: Part B, first: use your case's body and room temperatures from the Case record with the cooling rule to write the range cooling supports. Figure 2 shows the shape of the curve.
- • T6: Part B, second: use your case's rigor and livor findings from the Case record with Figure 3. Write the range each one supports on its own.
- • E1: A planned study connects its question to defined variables, controls, sampling, measurement, and analysis so the resulting data can support a bounded and reproducible conclusion.
- • E2: Define variables, controls, sampling, units, and the analysis plan before interpreting a result; analysis cannot repair biased or inconsistent measurement.
- • E3: You can compare STR bands lane by lane and turn each comparison into an exclusion statement.
Measurements: Use only the measurements, units, graph, or counts supplied in today's task. No additional patient measurement is implied.
Figure finding: Four stacked traces on a common size axis from about 60 to 360 , each in its own colour. D3S1358 in blue shows two peaks called 15 and 17. vWA in green shows two peaks called 16 and 18. FGA in amber shows two peaks called 22 and 24. Amelogenin in red shows two peaks called X and Y. Each trace has a vertical axis labelled RFU.
Uncertainty: This is a composite classroom scenario. Missing history, measurements, or confirmation tests remain unknown and limit the conclusion.
Students often think a strong match, a clear clock reading, or a positive test result settles the question. The trap: each one narrows the field and none of them closes it. A profile fails to exclude, a clock gives a window rather than a moment, and an test reports exposure rather than a diagnosis. The skill is naming what is left open.
- 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. Find it in Clever with your Microsoft sign-in, right next to Schoology.
Tap the speaker to hear a term. Add two of these to your notebook glossary with a definition and an example in your own words.
Pick just 2 or 3 words from today and make them yours: write what each one means in your own words, name the context clue or evidence that helped, then give one example from what you actually did in Week 5 review: the profile, the clock, and the two errors. Try your own words first; the glossary is there if you get stuck. This is voluntary and counts as extra credit, so keep it short.
Saved on this device. Show Mr. Mendoza or add these to your notebook glossary to claim the extra credit.
Part 2 of 4 · Directions in plain English▸
2.1 Open your materials
Case record: Case A, STATIC (Period 1-2)
Part A, the profile (Exhibit 012, from D10)
- The gel's left edge carries a migration scale from 10 (top) to 0 (bottom). A band's number is its position. Two bands at the same number line up.
- Questioned lane L1, console stain: bands at 7.5, 4.5 and 2.0.
- Reference lane L4, victim reference: bands at 7.5, 4.5 and 2.0.
- Reference lane L5, Cole reference: bands at 8.5, 5.5 and 3.0.
- Reference lane L6, Vasquez reference: bands at 6.5, 4.0 and 1.0.
- Make one call per reference lane: EXCLUDED if any band clearly differs, NOT EXCLUDED only if every band lines up.
Part B, the clock (from D12)
- Body temperature: 21.8 degrees C, taken at discovery, Monday 7:55 AM, in the studio.
- Room: 21 degrees C, steady all weekend, with the heating and cooling system on. The acoustic blanket covered the lower body.
- Rigor: fully passed, no stiffness anywhere.
- Livor: fixed (does not fade when pressed), on the front surfaces, which matches the face-down position the body was found in.
- Cooling rule from D12: the body cools from its normal living temperature, about 37 °C, toward room temperature at roughly 1 to 1.5 °C per hour early on. Write your assumptions with it.
Part C, the two errors (from the John Carroll case)
- The test is the ELISA antibody test for Novel Flu Syndrome (NFS) from the John Carroll debate.
- No counts and no error rate were given for this test, so do not make up numbers. For each of the four cells, write one example person instead.
2.2 Start the work
Head your record: Week 5 Review Record, your period, your code, and the date.
Show all 14 required steps
- Head your record: Week 5 Review Record, your period, your code, and the date.
- Part A, first: open the Case record in Part 2 of this page. Write down the three band positions of your questioned lane.
- Part A, second: compare them, band by band, with each of the three reference lanes in the Case record. For each reference write EXCLUDED or NOT EXCLUDED.
- Part A, third: under each call, write one sentence that says what the call does not prove. Use the pattern: 'This shows ___. It does not show ___.'
- Part B, first: use your case's body and room temperatures from the Case record with the cooling rule to write the range cooling supports. Figure 2 shows the shape of the curve.
- Part B, second: use your case's rigor and livor findings from the Case record with Figure 3. Write the range each one supports on its own.
- Part B, third: put the three ranges side by side and mark where they overlap. That overlap is your window. Write it as a range, never as one time.
- Part B, fourth: list the two assumptions your window rests on. Temperature and one other.
- Part C, first: using the 2x2 figure, label the four outcome cells in your own words.
- Part C, second: for the NFS antibody test from the John Carroll case, write one example person for each of the four cells. No counts are supplied, so do not make up numbers.
- Part C, third: answer in one sentence each, who is hurt by a false positive here, and who is hurt by a false negative here.
- Part D: write three sentences, one per tool, each naming what the tool shows and where it stops.
- Part E: run the 6 Rs once over the week, then write the one question you still have. A real question, not 'none'.
- Hand the paper record to Mr. Mendoza, or submit one PDF to Wk5 Lab: Body systems tissues in Schoology by 11:59 PM today. Do not do both.
Lost your place? Open your Week 5 Review Record and find the first unfinished Part. Start there. You do not need to redo the Parts you already have.
- 0 to 8Do Now, notes closed. Both questions, in writing.
- 8 to 25Part A, the profile. Read your case's STR lanes in the Case record, make your three calls, write the limit under each.
- 25 to 45Part B, the clock. Use your case's temperatures, rigor and livor with the figures, state your window and your assumptions.
- 45 to 60Part C, the two errors. Label the four outcomes with one example each, name who carries each harm.
- 60 to 72Part D, the ceiling. One sentence per tool: what it shows, what it does not.
- 72 to 80Part E, the pass and one open question. Hand in, or submit the PDF.
- • Friday is a strange one. The trip leaves at 11:20, pictures are happening, the STEM House meets, and some of you have games.
- • So nothing new today. Today you prove you still have the week.
- • Three tools: the profile, the clock, the two errors. One record, five Parts.
- • If you are going on the trip, you do not turn this in. Go and be excellent at the medical school.
- • Everyone else: this is the record that shows me you own Week 5.
PLTW connection and today's work
Today reviews Activity 1.2.2 Time of Death, with this week's DNA and testing work. There is no new myPLTW activity today.
Today's stopping point: Part E written, and the record handed in or submitted.
Today uses John Hay teacher-created practice. It builds skills for the course, but does not count as completing an official myPLTW activity.
Course connection
- Activity 1.2.2 Time of Death
Use the turn-in directions in Part 4 of this page. Do not create a second submission unless your teacher asks for one.
Show another explanation or a smaller first step
Need help? Choose a starting point
Part 3 of 4 · Worked example▸
This is a parallel case, not your own. Read it for the order of the work, then do your own in Part 4.
PART A (practice case, not your case). Questioned lane: bands at 6.0, 3.5 and 1.5.
Reference 1: bands at 6.0, 3.5 and 1.5. Band by band: 6.0 lines up, 3.5 lines up, 1.5 lines up. Call: NOT EXCLUDED.
This shows Reference 1 cannot be ruled out as the source of this sample. It does not show the sample came from Reference 1, and no rarity figure was supplied, so no strength can be stated.
Reference 2: bands at 6.0, 4.5 and 1.5. Band by band: 6.0 lines up, 4.5 does not line up with 3.5. One band that clearly differs is enough. Call: EXCLUDED.
This shows Reference 2 is not the source. It does not show who is.
PART B (practice case, not either section's case). Body 25 °C in a 20 °C room, found face-up. Cooling: 37 minus 25 is 12 degrees; 12 divided by 1.5 is 8 hours and 12 divided by 1 is 12 hours, so cooling alone supports roughly 8 to 12 hours.
Rigor: the whole body is stiff, jaw through legs. That sits near the peak the D12 schedule puts around 12 hours.
Livor: fixed (does not fade when pressed) on the back, which matches the face-up position. On its own that sets a floor of about 8 hours, with no ceiling.
Overlap: about 8 to 12 hours before the reading.
Assumptions: a 37 °C start and a steady room, and the body was not moved or covered after death.
PART C. True positive: test says infected, person is infected. False positive: test says infected, person is not. False negative: test says clear, person is infected. True negative: test says clear, person is not.
A false positive here is carried by the person labeled, who faces isolation and stigma they did not earn. A false negative is carried by everyone that person goes on to meet.
PART D. The profile shows a failure to exclude. It does not show identity.
The clocks show a window. They do not show an hour.
The antibody test shows current or past infection. It does not show an active illness or a diagnosis.
PART E. The R I actually skipped was Recite. I reread my notes and never once closed them and said it back. Open question: how much does a cold room widen the window in Part B, and is there a correction for it?
This model shows the level of evidence and organization needed to complete: A completed review record built from a different supplied case, so it models the sentence pattern without giving away any call on your own case.
- Date and label the entry.
- Record the procedure, observation, or design decision clearly.
- End with what the evidence means and the next step.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
Also due today: Write your own record on your own case. Hand it to Mr. Mendoza or submit one PDF. Trip students submit nothing.
A research team lays out its question, variables, controls, sampling plan, measurement record, and analysis before deciding what the data support.
- Which variable is changed or compared?
- Which conditions and measurements must stay consistent?
- Which conclusion is inside the study's evidence boundary?
Define variables, controls, sampling, units, and the analysis plan before interpreting a result; analysis cannot repair biased or inconsistent measurement.
A well-organized classroom study can still be limited by , measurement quality, confounding, and the population represented.
- • Question and variable cards map to the study design.
- • Control and measurement cards map to fair, reproducible data collection.
- • The conclusion card maps to a bounded claim supported by the analysis.
Part 4 of 4 · Your work▸
Check your work before submitting
- You can compare STR bands lane by lane and turn each comparison into an exclusion statement.
- You can build a time-of-death window from three clocks and name what it depends on.
- You can say who a false positive hurts and who a false negative hurts, and show they are different people.
- You can state the ceiling on every one of this week's tools without being prompted.
4.1 Turn in your work
DueCheck the Schoology assignment for this day- Hand in
- Week 5 Review Record, Parts A to E in one document: three STR calls with limits, a time-of-death window with its assumptions, the four labeled outcome cells with one example each, three ceiling sentences, and the 6 Rs pass with one open question.
How to submit and name your file
Hand the paper record to Mr. Mendoza at the end of the block, or submit one PDF to Wk5 Lab: Body systems tissues in your section's Schoology course. Due Friday, September 25, at 11:59 PM. Do not submit twice. If you are on the Health Education Campus trip, you do not submit this at all.
In Schoology, open your course and the assignment for this lesson. Attach your file, select Submit, and check that it appears in the submission.
PDF upload helpYou get two school days for every day you were absent, so this deadline moves with you.
Find this lesson's Schoology assignments
These are existing assignments for your section. Follow the directions in the assignment you are working on; this list does not add new work. A PLTW Work row repeats on every day of its lesson; submit it once. Check Schoology for each deadline.
Link will not open? Open Schoology, choose your course and section, and find the title shown above.
- 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.
- SubmittedGo to Schoology to turn this in. Submit one PDF. Schoology attaches your name to your upload; on the page itself, write your period and code. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf. If you cannot get in, see Mr. Mendoza. Do not skip the work.
How this lesson connects
Keep using what you learned last class: A position you cannot argue against is a position you do not yet hold; you have only inherited it. Today: Every tool this week narrows the field, and not one of them closes it.
Practice: try a question, then check your answer▸
Claim ceiling for this check: Today's evidence supports a classroom claim about today's lesson. It cannot prove causation, diagnose a real patient, or justify action outside this room.
Practice case, not your case. A body is found face-up at 10:00 PM. Its temperature is 25 °C in a 20 °C room, the whole body is stiff from the jaw to the legs, and the settled blood on the back does not fade when pressed. A student writes: 'Death occurred at 11:00 AM.' What is wrong with that sentence, and what should it say instead?
Write an answer and pick a confidence to unlock the key.
Fast retrieval with instant answers, not the commit-then-reveal check above. Try each from memory first: write what you remember about the earlier units, then check yourself here.
Missed class or ready for more?▸
Optional practice for this unit's lab skills. Nothing in it is due today. This lesson has more than one, and they cover different skills.
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.
Today is individual work you can do from home: complete the same target above, then submit your Notebook check.
Go to Schoology to turn this in. Submit one PDF. Schoology attaches your name to your upload; on the page itself, write your period and code. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf. If you cannot get in, see Mr. Mendoza. Do not skip the work.
Class still runs. Complete today's work as this page describes (it is self-guided). Need the concept taught without a teacher? Use this authoritative explainer:
Khan Academy: human body systems (Health and medicine)Sources: slides, readings, and resources▸
The deck carries the prior idea forward, lets you inspect an analogy, maps the rule to biology, and ends with the same evidence decision and exit ticket used on this page.
Hand-picked readings and interactives for this lesson, from authoritative open organizations and PLTW's own public course outline.
This week
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