Activity 1.4 — a 13-year-old girl is sick after a picnic. You have her medical file, the Disease Dictionary, and a lab. Name the invader.
4 days · Read the file like a detective, narrow the suspects, order a lab test,
read the result with controls, and tell the patient what happened.
Tap any glowing word for the meaning in English and Spanish.
You walk into the doctor's office with a stomach ache. Ten minutes later the doctor says what is wrong. How did they figure it out?
Two minutes. List every way a doctor collects clues: things they look at, things they measure, things they ask.
Hint: some clues come from the exam, some from tests — and a surprising number come from questions. Keep your list; you will check it against a real case today.
When the body is sick, it leaves clues. A doctor is a medical sleuth — a detective who gathers those clues from three places:
This activity is practice for the project coming up, where YOU solve a medical mystery from scratch. Today's patient is fictional. Her clues are not.
Two of these tell one story. Find them before you open the next tab.
Patient is a previously healthy 13-year-old girl, brought in by her mother. She says her stomach "hurts in waves" and she feels weak and thirsty.
Two days ago (Saturday, Sept. 25) the family went to a cousin's birthday picnic at the park. She ate grilled chicken, potato salad, deviled eggs, and homemade ice cream. The food sat out on the table through the hot afternoon.
Early the next morning — about 14 hours after the picnic — she woke up with stomach cramps. By breakfast she had watery diarrhea and had vomited twice. She has had a fever since then and has gone to the bathroom "too many times to count." She has not seen any blood.
Her mother says two cousins who ate the same food got sick the same night. Her younger brother, who ate only hot dogs and chips, feels fine. No one at school is sick that she knows of.
The family has not traveled and drinks regular tap water. She has not been around any babies or day-care children. She tries to drink water but "it comes right back up."
Tap every clue from the file that helps explain what is making her sick. Then tap Show the detective's board and compare.
Detective's rule: a clue about when it started, what she ate, and who else got sick is worth more than any single number. Write your list on Worksheet 1 — Diagnostic Clues.
The case notes did not write themselves. Tap every question the physician must have asked to get those notes. Then check.
On Worksheet 1 — Diagnostic Clues, finish the vital-sign table, list the clues from each tab, and write three questions the doctor asked.
Keep the list organized — by tab, not in a pile. Tomorrow you will use it to cross suspects off one at a time.
Exit ticket: the ONE clue you think matters most, and why.
"The clue that matters most is ______ because ______."
The Disease Dictionary lists sixteen illnesses. Guessing is not a strategy. Detectives use a funnel: ask a question that crosses off many suspects at once, then a second, then a third — until one is left.
Every question uses a column of the dictionary: symptoms, incubation period, transmission.
Warm-up first: from memory — what did Patient 1 eat, and how long after did she get sick?
Compare her symptoms to the Symptoms of Disease column. Watch for symptoms she does not have, too.
Count from contact to first symptoms. Compare to the Incubation Period column.
Read the Transmission column. Who else got sick? Any travel? What did she eat, drink, touch?
Question 1 alone cuts sixteen suspects to five — the ones whose main symptoms live in the gut. Questions 2 and 3 do the rest.
| Suspect | 1 · Symptoms match?diarrhea, vomiting, fever 101.3, cramps; no blood | 2 · Incubation fits?sick about 14 hours after the picnic | 3 · Spread fits?picnic food; cousins sick; no travel; tap water; no babies | ✔ total |
|---|
On Worksheet 2 — Narrow It Down, fill in the board, then write your diagnosis as a detective would — claim, evidence, reasoning.
Tomorrow the lab tests your answer. If the test comes back negative, you go back to the clues — that is not failing, that is diagnosing.
Which of the three funnel questions crossed off the most suspects for you — symptoms, timing, or spread?
"The ______ question did the most work because it crossed off ______."
Hand it in with Worksheet 2.
In Activities 1.2 and 1.3 you learned that a good experiment needs a control — something to compare against. Lab tests need them too. Every result comes with two controls:
Warm-up first: what is the control in an experiment, in one sentence?
Look at the patient sample. Which control does it match?
Round 1 is PLTW's own example (Disease A). The rounds after it get sneakier — including two where the test itself failed.
If the positive and negative controls come out the same color, the test did not work — maybe the chemicals were old, maybe a step was skipped. The patient's result means nothing that day.
Without controls you would never know. You would read a broken test as a real answer — and treat a patient for the wrong thing.
Same rule as Activity 1.3: if a ring showed up around the plain paper disc, the antibiotic did not deserve the credit. Controls catch the lie.
Pick the agent you diagnosed. The lab runs the test and hands back the result with both controls. You read it. Every test costs the family money — order the one your evidence points to first.
Tests ordered: 0 · Lab bill: $0
On Worksheet 3 — Positive or Negative?, record every test you ordered and what it showed. Then answer honestly:
Detectives who changed their answer did real science. The lab did not embarrass them — it gave them evidence.
Warm-up first: her diagnosis, the agent, and how she caught it — from memory. Then: the fever is the infection. The other two numbers are the water.
The dictionary says: treat the symptoms — fluid and salt replacement. Small sips, often. Broth, an oral rehydration drink, water with a little salt and sugar. Rest. Bland food when she can keep it down.
Antibiotics only for severe cases. Most people with this illness get better in 4 to 7 days without them — and needless antibiotics breed resistance (Activity 1.3).
Red flags that mean "come back now": cannot keep any fluid down, no urine for many hours, blood in the stool, fever climbing past 102.
Write all three on Worksheet 4 — Treatment & Conclusion. Then say them out loud to your partner as if they were the patient. No scary words, no blame.
A sick child sees someone in a white coat who examines, asks questions, diagnoses, and writes a prescription. Most people assume it was a doctor. Often it is an advanced practice provider — trained, certified, and licensed to do those things.
Real diagnosis is a team sport — nurses, providers, lab techs, and the patient's family all add clues. Talk with your partner, then write:
On Worksheet 4 — Treatment & Conclusion, Part C.
Claim — one sentence. Evidence — a control, a clue from the file, a dictionary fact. Reasoning — connect them.
Both answers go on Worksheet 4 — Treatment & Conclusion, Part D.
You read a medical file, funneled sixteen suspects down to one, ordered a lab test, and read it with controls. That is exactly how a real diagnosis works.
Next up: Project 1.5 — Diagnostic Detectives, where the file is yours to build.
Every academic word in Medical Detectives so far. Tap one for the full card.
Click any slide to jump there.