Concentration and serial dilution
Safety gate · before any work
- 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.
Do now
Calculate concentrations and plan a serial dilution so you can prepare known sample strengths.
- Hand in
- Four-step 1:10 serial dilution plan with concentration calculated at each step, plus a one-sentence prediction of signal change.
- Where
- Turn this in at the drop folder with your district Microsoft sign-in, or hand it to Mr. Mendoza in class. Both count as submitted. Doing the activity in myPLTW does not.
You get two school days for every day you were absent, so this deadline moves with you.
The clinic needs to measure how much virus is in a patient's blood, but the sample just looks like a faint color. How do you make a set of known strengths precise enough to pin that color to an actual number?
Calculate concentrations and plan a so you can prepare known sample strengths.
- • You will be able to define and calculate concentration.
- • You will be able to plan a and predict each step's concentration.
- • You will be able to explain why dilutions matter for measurement.
- If you mix 1 part juice with 9 parts water, is the juice now stronger or weaker, and by about how many times?
- Why can't you just look at a colored liquid and know its exact concentration?
- 1Define concentration in your notebook as amount of substance per volume.
- 2Read the serial-dilution example, then write what a 1:10 dilution does to concentration.
- 3Plan a four-step 1:10 and write the concentration at each step.
- 4Double-check your math: each step should be one-tenth of the step before.
- 5Predict how the color or signal would change down a dilution series.
- 6Write one sentence on why dilutions are useful for building a .
What did this day actually feel like?
Concentration and serial dilution
Serial dilution: each step is the same fixed reduction, so ten of them get you very small very fast. It is the only practical way to get to the concentrations these assays need.
The arithmetic is easy and doing it correctly under time pressure with real tubes is not, which is why we did it on paper first.
AT HOME, THE NIGHT BEFORE THU SEP 17 Standard curve and lab prep The standard curve is the thing that makes a colour mean a number. Known concentrations, measured responses, a line through them, and then you read your unknown off the line.
Without it an ELISA tells you something is present. With it you know how much.
Turned in: pre-lab → recorded in Class Records
Fiction. There is no such student. The lessons, labs and dates are the real planned course; the student, the classmates and the conversations are invented.
The same day, drawn.
Serial dilution: each step is the same fixed reduction, so ten of them get you very small very fast. It is the only practical way to get to the concentrations these assays need.
Fiction. There is no such student. The lessons, labs and dates are the real planned course; the student, the classmates and the conversations are invented.
🛠 Get unstuck · pick your level
Lab day: Tier 1 is the whole class at the bench. No extension today.
🔑 Today's words · 5
Tap a word in the lesson for a plain meaning and one example. Recycled into next week's Do-Now.
Do the work · 80-minute blockfirst 5 min = hook▸
💡 Big idea: A repeats the same known at each step, so it builds a ladder of exactly-known concentrations you can later use to measure an unknown.
- 0-10 minDefine concentration and in notebook; review C1V1 = C2V2 if needed
- 10-25 minWork through the example: a 1:10 starting from a known stock, four steps
- 25-40 minPlan your own four-step 1:10 ; write concentration at each step; double-check math
- 40-55 minPredict how color/signal intensity would change down the series and explain why
- 55-70 minWrite one sentence connecting serial dilutions to construction
- 70-80 minPartner check: swap plans and verify each other's concentrations at every step
- • Every ever run in a clinical lab starts with a set of known standards; without them you have a signal but no meaning.
- • is one of the most fundamental techniques in all of biochemistry and molecular biology.
- • Today you master the math so that Wednesday's lab prep is a calculation you can do from memory.
- • Exit goal: a four-step dilution plan with correct concentrations at each step and a prediction sentence.
- • Concentration is the amount of a substance dissolved in a given volume; a 1:10 dilution means one part sample to nine parts solvent.
- • A creates a sequence of known concentrations by repeating the same at each step.
- • A plots signal versus known concentration, allowing you to read off the concentration of any unknown sample.
Concentration, serial dilution, standard curves, antigen–antibody binding, direct vs. indirect ELISA. · Concentration and
Day 2 of this lesson. Open this exact section in myPLTW (find it in Clever, Microsoft sign-in), then do the work below.
Do this: Open Activity 1.1.4 Serial Dilutions in myPLTW and work through the concentration and dilution calculation examples.
Write your four-step 1:10 plan with concentration at each step and submit it.
Monday debate CER should be posted; dilution plan due today.
Dilution plan with four concentration values in notebook.
The official PLTW activity stays inside myPLTW. If myPLTW will not open, use F1 and E1-E3 on this page to complete today's local evidence decision, then make up the official activity when access returns. Turn this in at the drop folder with your district Microsoft sign-in, or hand it to Mr. Mendoza in class. Both count as submitted. Doing the activity in myPLTW does not.
Check things off as you work, then submit. This tells Mr. Mendoza how you're doing so he can help the class. It does not replace turning in your producible through the submission route shown below.
Use the code Mr. Mendoza gave you, not your name. Saved on this device.
Concentration, serial dilution, standard curves, antigen–antibody binding, direct vs. indirect ELISA. · Concentration and serial dilution
Open Activity 1.1.4 Serial Dilutions in myPLTW and work through the concentration and dilution calculation examples.
Monday debate CER should be posted; dilution plan due today.
This is how Mr. Mendoza sees the class keeping pace with PLTW. Be honest, it only helps if it is accurate.
🎯 Calculate concentrations and plan a so you can prepare known sample strengths.
- Define concentration in your notebook as amount of substance per volume.
- Read the serial-dilution example, then write what a 1:10 dilution does to concentration.
- Plan a four-step 1:10 and write the concentration at each step.
- Double-check your math: each step should be one-tenth of the step before.
- Predict how the color or signal would change down a dilution series.
- Write one sentence on why dilutions are useful for building a .
Data table: Four-step 1:10 plan with concentration calculated at each step, plus a one-sentence prediction of signal change.
Turn this in at the drop folder with your district Microsoft sign-in, or hand it to Mr. Mendoza in class. Both count as submitted. Doing the activity in myPLTW does not. Use the checklist just below and upload by 11:29 PM for full credit. Absent with an excused absence? You get two school days for every day you were absent, so this deadline moves with you.
| Task | Who |
|---|---|
| Define concentration in your notebook as amount of substance per volume. | _______ |
| Read the serial-dilution example, then write what a 1:10 dilution does to concentration. | _______ |
| Plan a four-step 1:10 and write the concentration at each step. | _______ |
| Double-check your math: each step should be one-tenth of the step before. | _______ |
| Predict how the color or signal would change down a dilution series. | _______ |
| Write one sentence on why dilutions are useful for building a . | _______ |
Working solo? Put your own name in "Who" for every row.
- You will be able to define and calculate concentration.
- You will be able to plan a and predict each step's concentration.
- You will be able to explain why dilutions matter for measurement.
- 1Do thisCalculate concentrations and plan a serial dilution so you can prepare known sample strengths.
- 2Use this resource
- 3Submit thisData table: Four-step 1:10 serial dilution plan with concentration calculated at each step, plus a one-sentence prediction of signal change.
- 4Submit it here
- 1Open the drop folder.
- 2Sign in with your district Microsoft account, not a personal one.
- 3Upload the file, named Lastname_Firstname__Assignment Title.
- 4Your own upload panel says Uploaded with a green check: that is your receipt.
Turn this in at the drop folder with your district Microsoft sign-in, or hand it to Mr. Mendoza in class. Both count as submitted. Doing the activity in myPLTW does not. Genetics of Disease (Medical Interventions) › Concentration, serial dilution, standard curves, antigen–antibody binding, direct vs. indirect ELISA. › Data tableOpen the drop folder
Learn it · deck, reading, 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.
Every allocation rule advantages some people and excludes others, so a fair decision has to name and defend its tradeoff rather than pretend it is neutral.
A repeats the same known at each step, so it builds a ladder of exactly-known concentrations you can later use to measure an unknown.
An airport checkpoint uses several imperfect checks before deciding what action to take.
- What can each check detect?
- What might create a false alarm?
- Why is one result not always enough?
A decision is stronger when the test fits the question and its limits are known.
Medical decisions also depend on biology, patient context, ethics, and professional judgment.
- • Checkpoint evidence maps to E1-E3.
- • False alarms map to test limitations.
- • The response maps to the justified next intervention or test.
Driving question: The clinic needs to measure how much virus is in a patient's blood, but the sample just looks like a faint color. How do you make a set of known strengths precise enough to pin that color to an actual number?
What you already know: Every allocation rule advantages some people and excludes others, so a fair decision has to name and defend its tradeoff rather than pretend it is neutral.
New idea: A repeats the same known at each step, so it builds a ladder of exactly-known concentrations you can later use to measure an unknown.
Visual or model: F1. F1. A lesson illustration or teaching diagram for Concentration and serial dilution. Use it with E1-E3; it is a model or context image, not experimental or patient data. What to notice: Trace the labeled testing, treatment, or biological process and identify where evidence limits the decision.
- Observe or measure the relevant feature in Concentration and .
- Organize the observation with a stable evidence ID.
- Apply this rule: A decision is stronger when the test fits the question and its limits are known.
- Choose the option the evidence supports and state the limit of the conclusion.
Real biomedical example: The clinic needs to measure how much virus is in a patient's blood, but the sample just looks like a faint color. How do you make a set of known strengths precise enough to pin that color to an actual number?
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.
- • : A molecule, often on a germ's surface, that the immune system recognizes as foreign and responds to by making matching antibodies.
- • : A Y-shaped made by the immune system that binds to a specific foreign target, marking it for destruction or blocking its effect.
- • : A lab test that uses antibodies linked to an to detect and measure a specific , with a color change signaling its presence.
- • : A stepwise process of repeatedly diluting a sample by the same factor to make a range of lower, known concentrations.
- • : A graph made from samples of known concentration, used to read off the unknown concentration of a test sample from its measured signal.
- • : The specific molecule an acts on, fitting into the enzyme's active site so it can be changed into a product.
- • : A measure of how much light a sample blocks at a given wavelength, used to estimate how concentrated a substance is in a solution.
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.
Concentration is the amount of a substance dissolved in a given volume; a 1:10 dilution means one part sample to nine parts solvent.
Limit: E1 supplies context or an observation; it does not by itself establish the explanation.
A repeats the same known at each step, so it builds a ladder of exactly-known concentrations you can later use to measure an unknown.
Limit: E2 is a teaching statement or comparison and must be checked against the task evidence.
You will be able to define and calculate concentration.
Limit: E3 supports only the result or product criterion named here; it cannot justify a broader clinical or causal claim.
PLTW-GEND-2026-09-16 · Simulated classroom evidence scenario
Your role: medical interventions team member
Decision: Your team must decide what the evidence from Concentration and supports before submitting the labeled and result claim named on the lesson page.
- • Select the option best supported by E1-E3.
- • Select a reasonable alternative and name the evidence it would require.
- • Delay the claim because the evidence does not distinguish the options.
Response: State one choice, cite at least two evidence IDs, explain the rule that connects them, and add one limitation. Submit it as the labeled and result claim.
Claim ceiling: The supplied lesson evidence can support an observation, pattern, classroom mechanism, or next-step decision about Concentration and . It cannot by itself prove causation, establish a real clinical diagnosis, or justify action outside this classroom task.
Reason for review: Your team must decide what the evidence from Concentration and supports before submitting the labeled and result claim named on the lesson page.
Context: You cannot read a concentration straight off a sample, but you can build a ladder of known concentrations and use it as a ruler, so measuring the unknown becomes a matter of comparing it to knowns you made on purpose.
- • T1: Define concentration in your notebook as amount of substance per volume.
- • T2: Read the serial-dilution example, then write what a 1:10 dilution does to concentration.
- • T3: Plan a four-step 1:10 and write the concentration at each step.
- • T4: Double-check your math: each step should be one-tenth of the step before.
- • T5: Predict how the color or signal would change down a dilution series.
- • T6: Write one sentence on why dilutions are useful for building a .
- • E1: Concentration is the amount of a substance dissolved in a given volume; a 1:10 dilution means one part sample to nine parts solvent.
- • E2: A repeats the same known at each step, so it builds a ladder of exactly-known concentrations you can later use to measure an unknown.
- • E3: You will be able to define and calculate concentration.
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 Concentration and . Trace the labeled testing, treatment, or biological process and identify where evidence limits the decision. 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.
For a linear , y = mx + b. To estimate an unknown concentration, use x = (y - b) / m.
A is y = 0.40x + 0.10. An unknown signal is 0.90. x = (0.90 - 0.10) / 0.40 = 2.0 concentration units.
Signal units belong on y. Concentration units belong on x. Confirm the unknown falls inside the standards before interpreting it.
Use the equation or graph supplied today to estimate one unknown. Show the substitution, concentration unit, and range check.
- • The solution must address the stated need in Concentration and .
- • 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 often read a 1:10 dilution as 'divide the concentration by 9,' because they count the 9 parts of water and stop there.. The trap: A 1:10 dilution divides the concentration by 10, not 9, because the total volume is 1 part sample plus 9 parts solvent, which is 10 parts total. The sample is now 1 out of 10 parts, so it is one-tenth as strong. Count the whole final volume, not just the water you added.
This is a parallel example on a 1:2 series, so you can see the format and then build your own plan for today's dilution.
A 1:2 dilution means one part sample to one part solvent, which makes each step half as concentrated as the step before.
Prediction: as concentration is cut in half at each step, the color or signal should get steadily weaker down the series, but more gradually than a tenfold series.
Why dilutions help: a row of known concentrations is exactly what you need to build a standard curve and read an unknown sample.
| Step | Dilution from start | Concentration |
|---|---|---|
| Start | none | 800 ng/mL |
| Step 1 | 1:2 | 400 ng/mL |
| Step 2 | 1:2 again | 200 ng/mL |
| Step 3 | 1:2 again | 100 ng/mL |
| Step 4 | 1:2 again | 50 ng/mL |
This model shows the level of evidence and organization needed to complete: A worked parallel example on a different factor, a 1:2 titration: a four-step plan showing the concentration at each step, with a one-sentence prediction of how the signal changes down the series. Use it to model the format, then build your own plan for today's numbers.
- Name the variables and include units.
- Enter observations without changing the raw values.
- Check labels, calculations, and patterns before interpreting the data.
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: Keep in notebook; bring to Wednesday's lab prep session.
- 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 Concentration and serial dilution. 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.
Classroom documents for this lesson are posted in Schoology. Open Clever, then Schoology, and find each one by the name shown on its card.
Use this if you were absent, got stuck, or need another pass before you submit the lesson artifact.
Placement rationale
Matched model, dilution, by path:Medical-Interventions/Unit-1_How-to-Fight-Infection/1.1_The-Mystery-Infection; keywords:elisa, , dilution. Score 154. Visibility: student-schoology (student-facing resource; link through Schoology rather than local path).
Open this when the class reaches this activity and use it to complete the required lesson artifact.
Placement rationale
Matched model, dilution, by path:Medical-Interventions/Unit-1_How-to-Fight-Infection/1.1_The-Mystery-Infection; keywords:elisa, . Score 146. Visibility: student-schoology (student-facing resource; link through Schoology rather than local path).
Use this if you were absent, got stuck, or need another pass before you submit the lesson artifact.
Placement rationale
Matched model, dilution, by path:Medical-Interventions/Unit-1_How-to-Fight-Infection/1.1_The-Mystery-Infection; keywords:, dilution. Score 142. Visibility: student-schoology (student-facing resource; link through Schoology rather than local path).
How to get there: open Clever and sign in with your Microsoft (district) account. Both myPLTW and Schoology are in Clever. Do the activity in myPLTW. Turn the work in on this site or hand it to Mr. Mendoza, because that is the step that counts as submitted. Schoology only shows your report-card grade later.
Check yourself · commit, then reveal▸
Claim ceiling for this check: The supplied lesson evidence can support an observation, pattern, classroom mechanism, or next-step decision about Concentration and . It cannot by itself prove causation, establish a real clinical diagnosis, or justify action outside this classroom task.
You start with a solution at 1000 units/mL and do a four-step 1:10 serial dilution. What is the concentration after the fourth dilution?
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.
Go further and get help▸
I can name the procedure's purpose and the evidence I will record. I can identify each named hazard and the control that reduces it: 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. 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.
- 2Define concentration in your notebook as amount of substance per volume.
- 3Read the serial-dilution example, then write what a 1:10 dilution does to concentration.
- 4Plan a four-step 1:10 serial dilution and write the concentration at each step.
- 5Double-check your math: each step should be one-tenth of the step before.
- 6Predict how the color or signal would change down a dilution series.
- 7Write one sentence on why dilutions are useful for building a standard curve.
- 8Record each result in the prepared table before interpreting it. Mark missing, repeated, or invalid results truthfully.
- 9Complete 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 Data table.
Open the drop folderTurn this in at the drop folder with your district Microsoft sign-in, or hand it to Mr. Mendoza in class. Both count as submitted. Doing the activity in myPLTW does not.
Class still runs. Complete the online activity above (it's self-guided). Need the concept taught without a teacher? Use this authoritative explainer:
HHMI BioInteractive (preview; use fallback if blocked)- 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.
- SubmittedTurned in the right way, on the class site or handed to Mr. Mendoza in class, and confirmed. Not in Schoology: that is where the report-card grade appears later.
- 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.