Infection-control case
Open your materials, follow the steps, then turn in your work.
Students analyze a hospital scenario to identify breaks in the chain of infection and prescribe controls.
1. Open your materials
Use the materials named in the first step below. Open lesson resources.
2. Start the work
Record the SOP for hand hygiene and PPE donning and doffing.
Show all 5 required steps
- Record the SOP for hand hygiene and PPE donning and doffing.
- Identify the variables in the scenario that raise or lower transmission risk.
- Trace the chain of infection for one patient and locate the weakest link.
- Recommend a specific aseptic intervention that breaks that link.
- Document one limitation in your data or assumptions.
Lost your place? Lost your place (this is your pre-lab)? You should have the SOP recorded and the scenario variables identified. If you have not yet traced one patient's chain to its weakest link, resume at step 3 before writing your intervention.
Check your work before submitting
- Identify a specific break in the chain of infection from the scenario.
- Recommend a control measure and state one limitation.
Before lab work: read the safety rules
- Wear the required PPE, keep the bench clear, handle equipment only as directed, and know where the eyewash, sink, and spill kit are before you start.
- Human samples and data stay private: label with a code, never a name, and dispose of materials in the correct waste container, then wash your hands.
3. Turn in your work
DueCheck Schoology- Hand in
- Written analysis identifying the weakest chain-of-infection link in the scenario, naming the aseptic intervention, and stating one limitation.
How to submit and name your file
Use the submission route shown on today's today's page.
In Schoology, open your course and the assignment for this lesson. Attach your file, select Submit, and check that it appears in the submission.
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Find this lesson's Schoology assignments
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How this lesson connects
Keep using what you learned last class: Infection spreads through six ordered links, so breaking any single link stops transmission because the germ can no longer complete its path to a new host. Today: You must locate the single weakest link in a specific case before prescribing a control, because a targeted fix aimed at the real weak point works while a general hygiene tip cannot be tested or aimed.
Check you have the right sheet: the top of it prints today's portal day, Infection-control case. The PLTW activity itself is in myPLTW and is not posted here.
Optional: listen or watch a unit review▸
Need help? Warm-up, timing, and directions▸
💡 Big idea: You must locate the single weakest link in a specific case before prescribing a control, because a targeted fix aimed at the real weak point works while a general hygiene tip cannot be tested or aimed.
- 0-8 minRecord the hand hygiene and PPE donning/doffing SOP in your notebook.
- 8-18 minRead the hospital scenario; identify variables that raise or lower risk.
- 18-40 minTrace the chain of infection for the case patient; mark the weakest link.
- 40-58 minWrite a specific intervention that breaks the weakest link, with chain-based reasoning.
- 58-70 minDocument one data limitation or assumption that could change the recommendation.
- 70-80 minShare chain finding with a partner; confirm you agree on which link is weakest.
- • You traced the chain of infection in notes yesterday; today you apply it to a real hospital scenario.
- • The SOP for PPE donning and doffing is a handling and preparation skill tested on WebXam 072110 strand 5.
- • Your recommendation must name the specific chain link it breaks, not just say 'wash hands more.'
- • One limitation is required: every control has a failure mode, and naming it is intellectual honesty.
- • Each variable in a hospital scenario (patient immune status, staff behavior, environment) maps to a specific chain link.
- • An effective infection-control recommendation names the exact link it targets, not just a general hygiene tip.
- • Data limitations reveal where the recommendation could fail if assumptions are wrong.
PLTW connection and today's work
In myPLTW, open Lesson 3.1 Nosocomial Nightmare and go to Activity 3.1.3 Modes of Transmission. Use it to check your scenario analysis.
Today's stopping point: Platform prompts should be done by mid-period; the written recommendation is today's primary product.
PLTW activity titles identify the course connection. If your account will not open, use the posted materials for today and tell Mr. Mendoza. Do not mark an online activity complete unless you completed it.
Course connection
- Activity 3.1.3 Modes of Transmission
Use the turn-in directions at the top 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
Finish the assigned lab safely before starting extra practice.
Lesson resources: reading, slides, and vocabulary▸
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.
Generated from this lesson's canonical data with a red-team citation check.
Infection spreads through six ordered links, so breaking any single link stops because the germ can no longer complete its path to a new host.
You must locate the single weakest link in a specific case before prescribing a control, because a targeted fix aimed at the real weak point works while a general hygiene tip cannot be tested or aimed.
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.
Driving question: Given one patient's immune status, the staff's habits, and the room's conditions, which one of those details is the weakest link letting infection through?
What you already know: Infection spreads through six ordered links, so breaking any single link stops because the germ can no longer complete its path to a new host.
New idea: You must locate the single weakest link in a specific case before prescribing a control, because a targeted fix aimed at the real weak point works while a general hygiene tip cannot be tested or aimed.
Visual or model: F1. F1. A lesson illustration or teaching diagram for Infection-control case. Use it with E1-E3; it is a model or context image, not experimental or patient data. What to notice: Trace the labeled observation or evidence sequence before choosing an explanation.
- Observe or measure the relevant feature in infection-control case.
- 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: Given one patient's immune status, the staff's habits, and the room's conditions, which one of those details is the weakest link letting infection through?
What the evidence supports: E1-E3 and F1 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.
- • nosocomial: Describes an infection that a patient catches while in a hospital or healthcare setting rather than bringing it in from outside.
- • : A microorganism such as a bacterium, virus, fungus, or parasite that can cause disease in its host.
- • vector: A that delivers genetic material into a cell, such as a or virus, or an organism like a mosquito that spreads a disease.
- • reservoir: A living host or environment where a normally lives and multiplies, serving as the source from which infections spread.
- • : The passing of a disease-causing agent from one host to another, by routes such as contact, droplets, contaminated objects, or vectors.
- • : The body's coordinated defense against a harmful invader, in which immune cells recognize, attack, and remember the threat.
- • PPE: Personal protective equipment, the gear like gloves, goggles, lab coats, and masks worn to shield the body from chemical, biological, or physical hazards.
- • : Describing techniques that keep an area free of harmful microbes so cultures and patients are not contaminated.
Use it now: Choose one decision option. Cite E1 and E3, then explain how the rule connects the evidence to your choice.
Go further, optional: The source links below are optional enrichment. Every fact required for today's local evidence decision appears in this lesson package.
Infection prevention targets links that allow an infectious agent to reach a susceptible host, and the selected control must match the route and evidence in the case.
Limit: The classroom chain model simplifies host, , environment, timing, and implementation factors and cannot establish a real outbreak source.
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.
Identify a specific break in the chain of infection from the scenario.
Limit: E3 defines the classroom product or success criterion. It is not independent scientific evidence and cannot justify a clinical or causal claim.
PLTW-PBT-2026-11-18 · Simulated classroom evidence scenario
Your role: biomedical investigator
Decision: Your team must decide what the evidence from infection-control case supports before submitting the pre-lab readiness record named on today's page.
- • Restate your control claim in fuller sentences for the reasoning section, since that is what reasoning is meant to do.
- • Hold the predicted risk drop until we know this unit's infection rate before the control was put in place.
- • Write reasoning that explains the mechanism by which breaking your chosen link cuts infection, not a longer claim.
Response: State one choice, cite at least two evidence IDs, explain the rule that connects them, and add one limitation. Submit it as the pre-lab readiness record.
Claim ceiling: Today's evidence supports a classroom claim about infection-control case. 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 infection-control case supports before submitting the pre-lab readiness record named on today's page.
Context: Good infection control aims at one identified weak link. Find the link that is actually open in the situation in front of you, then choose the control that closes it.
- • T1: Record the SOP for hand hygiene and PPE donning and doffing.
- • T2: Identify the variables in the scenario that raise or lower risk.
- • T3: Trace the chain of infection for one patient and locate the weakest link.
- • T4: Recommend a specific intervention that breaks that link.
- • T5: Document one limitation in your data or assumptions.
- • E1: Infection prevention targets links that allow an infectious agent to reach a susceptible host, and the selected control must match the route and evidence in the case.
- • E2: Define variables, controls, sampling, units, and the analysis plan before interpreting a result; analysis cannot repair biased or inconsistent measurement.
- • E3: Identify a specific break in the chain of infection from the scenario.
Measurements: Use only the measurements, units, graph, or counts supplied in today's task. No additional patient measurement is implied.
Figure finding: Teaching diagram for Infection-control case. Trace the labeled observation or evidence sequence before choosing an explanation. This is a teaching model, not patient or experimental data.
Uncertainty: This is a composite classroom scenario. Missing history, measurements, or confirmation tests remain unknown and limit the conclusion.
Rate or percent = part / comparison total x 100%. Percent change = (new - comparison) / comparison x 100%.
If 18 of 60 records meet a condition, the frequency is 18 / 60 x 100% = 30%.
Name the comparison total. A percent describes the supplied group and does not automatically predict an individual's outcome.
Use today's supplied counts to calculate one rate, risk, frequency, or percent change. Show the denominator and interpretation.
- • The solution must address the stated need in infection-control case.
- • The decision must be supported by E1-E3.
- • The final product must make the success criteria visible.
- • Complete the work inside the 80-minute block.
- • Use only supplied or teacher-approved materials and evidence.
- • Do not trade , accessibility, or privacy for speed.
- • and evidence quality: must pass before scoring other criteria.
- • User need and effectiveness: highest scored criterion.
- • Time, cost, and ease of use: compare only after and effectiveness pass.
Test evidence: For each option, record the E1-E3 result that supports or fails each criterion. Do not assign a score without a named observation.
- Version or option tested
- Criterion met or missed
- Evidence ID and result
- Revision made
- Reason for the revision
- Need and user
- Criteria and constraints
- Chosen option and evidence
- Test result
- Revision and reason
Students often think Students think a good recommendation is to improve hygiene everywhere in the scenario at once.. The trap: A recommendation that targets everything targets nothing, because you cannot tell if it worked or where to spend limited time and money. A strong control names the exact link it breaks, so the fix is testable and the weakest point actually gets closed.
Scenario summary: Patient A is recovering from abdominal surgery in a shared room. A staff member moved between Patient A and a patient with a draining wound without changing gloves. Patient A is on a medication that lowers immune function.
SOP I recorded for hand hygiene and PPE:
- Wash or sanitize hands before and after every patient contact.
- Don gloves and gown before touching a wound, doff them before leaving the bedside, then sanitize again.
Risk variables I identified:
- Patient immune status: lowered, which raises susceptibility.
- Staff behavior: gloves not changed between patients, which raises transmission risk.
- Environment: shared room with a draining-wound patient nearby, which raises exposure.
Chain trace for Patient A:
- Agent: wound bacteria from the neighboring patient.
- Reservoir: the draining wound.
- Portal of exit: wound drainage on the staff member's gloves.
- Mode of transmission: contaminated gloves carried to Patient A.
- Portal of entry: Patient A's surgical incision.
- Susceptible host: Patient A, immune-suppressed.
Weakest link: the mode of transmission, because the same gloves carried bacteria directly from one patient to another.
Recommended intervention: enforce glove change plus hand hygiene between every patient. This breaks the transmission link before bacteria can reach Patient A's incision.
Limitation: I assumed the neighboring wound is the source. If Patient A's own skin flora caused the infection, the glove-change rule would not be the highest-priority fix.
This model shows the level of evidence and organization needed to complete: Completes the infection-control case prep: a written analysis that traces the chain of infection for one patient, names the weakest link, prescribes one aseptic intervention, and states a limitation.
- Identify the purpose, hazards, and required controls.
- Write the procedure in a usable order.
- Confirm materials, measurements, and waste handling before starting.
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: Submit your written case analysis on Schoology.
- 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 Infection-control case. 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.
Hand-picked readings and interactives for this lesson, from authoritative open organizations and PLTW's own public course outline.
Practice: try a question, then check your answer▸
Claim ceiling for this check: Today's evidence supports a classroom claim about infection-control case. It cannot prove causation, diagnose a real patient, or justify action outside this room.
A chemotherapy patient (very low white-blood-cell count) is on a unit with good handwashing but a reused, poorly cleaned blood-pressure cuff moving room to room. Which link is the weakest here, and what single control targets it?
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?▸
Run this before you touch the bench. It is built from the real lab procedure, so the decisions you make here are the ones you will make with the equipment in your hands.
I can name the procedure's purpose and the evidence I will record. I can state today's specific hazards and the control for each. If this deck does not name them, I ask Mr. Mendoza before I touch anything. My data table is ready before materials are handled.
Finish the checklist before you handle any material.
- • Wear the required PPE, keep the bench clear, handle equipment only as directed, and know where the eyewash, sink, and spill kit are before you start.
- • Human samples and data stay private: label with a code, never a name, and dispose of materials in the correct waste container, then wash your hands.
- 1Before materials are handled, identify the purpose, variables or comparison, controls, measurement units, and stop-work condition.
- 2Record the SOP for hand hygiene and PPE donning and doffing.
- 3Identify the variables in the scenario that raise or lower transmission risk.
- 4Trace the chain of infection for one patient and locate the weakest link.
- 5Recommend a specific aseptic intervention that breaks that link.
- 6Document one limitation in your data or assumptions.
- 7Record each result in the prepared table before interpreting it. Mark missing, repeated, or invalid results truthfully.
- 8Complete the named cleanup and waste route, remove PPE safely, wash hands when required, and confirm the station is ready for the next group.
| Trial or sample ID | Independent condition | Measured result with units | Observation before interpretation | Quality-control note |
|---|---|---|---|---|
Before the procedure, predict the result and cite the rule behind the prediction.
After the procedure, compare the result with the prediction and name one limitation or source of uncertainty.
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 Pre-lab.
Go to Schoology to turn this in. Submit one PDF. Put your first and last name in the document header. 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 the online activity above (it's self-guided). Need the concept taught without a teacher? Use this authoritative explainer:
CDC: infection control basics and the chain of infectionYou've passed Unit 2, so the optional extra-credit track is open. Complete reserved-unit work from home, including virtual labs, for extra credit. Each item shows its correct submission route.
Open the extra-credit track- 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. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf. If you cannot get in, see Mr. Mendoza. Do not skip the work.
- Error analysis and method · counts doubleName a specific limit of the method and how it moved your result, and compare what you predicted to what happened. "Human error" does not count; say what about the procedure or instrument caused it.
This week
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