MI / Genetics of Disease · September 17, 2026 · 80 minutes
Separate worked model: four 1:2 steps
Method support, not the assigned data or a second submission
One PDF, due September 17 at 11:59 p.m. If I collected the same work on paper, do not upload it again.
Separate worked model: four 1:2 steps
Method support, not the assigned data or a second submission
This example shows the method using a different starting value, dilution factor and unit. It is not your assigned data or a second submission. Your assignment starts at 1000 units/mL and uses four 1:10 steps. This model starts at 800 ng/mL and uses four 1:2 steps. The unit ng/mL means nanograms per milliliter. Do not substitute it for units/mL in your assigned record.
Model input and rule
The starting value is illustrative, not measured. Each 1:2 model step uses one part preceding sample plus one part solvent, or two total parts. Divide the preceding concentration by 2. Use the result from each row as the input to the next.
| Row | Preceding concentration | Calculation | Resulting concentration |
|---|---|---|---|
| Starting stock, given | Not applicable | Given illustrative input | 800 ng/mL |
| Step 1 | 800 ng/mL | 800 ÷ 2 | 400 ng/mL |
| Step 2 | 400 ng/mL | 400 ÷ 2 | 200 ng/mL |
| Step 3 | 200 ng/mL | 200 ÷ 2 | 100 ng/mL |
| Step 4 | 100 ng/mL | 100 ÷ 2 | 50 ng/mL |
This table has a starting-stock row plus four dilution steps. Each calculation divides the preceding value, not a fresh copy of the starting value. The concentration unit remains ng/mL throughout this separate model.
Model prediction and its limit
Assumption: For this classroom model, assume signal increases with concentration within its useful range. The prediction is conditional on that assumption, not a rule for every assay format.
Example sentence: If signal increases with concentration within the model's useful range, the planned decrease in concentration across these four 1:2 steps would predict a weaker signal; this is a conditional prediction, not a measured result.
The calculation does not show what was actually mixed, establish an assay result or diagnose a patient. No sample or equipment is used in this paper model.
Apply the method to your own record
Use the assigned illustrative 1000 units/mL starting value and 1:10 ratio. Count one sample part plus nine solvent parts as ten total parts. Complete the four blank step rows using the preceding row each time, keep units/mL, and write your own conditional prediction using the assumption beside its field.
Return to today's portal lesson for the blank record. Submit only your completed assigned table and prediction as one PDF to Wk4 Data table: Concentration and serial dilution by September 17 at 11:59 PM. If I collected that work on paper, do not upload it again. This model and guided notes are not submissions.
The method supports the PLTW Serial Dilutions resource connected to Activity 1.1.5, ELISA. This paper model does not complete the official activity or assign an assay. ELISA background is an existing supporting reference.
Connection to PLTW
This local paper-planning task supports the Serial Dilutions resource connected to PLTW Medical Interventions Activity 1.1.5, ELISA. It practices ratio and concentration reasoning. It does not by itself complete the official activity or assign an assay.
- PLTW Activity 1.1.5: ELISA: Existing official source reference; not an instruction to perform the full activity
- PLTW Serial Dilutions resource: Existing official reference; all inputs for today's local task are supplied here
- Sign in to myPLTW: Existing authorized curriculum access route
- ELISA background and assay limits: Previously approved scientific background, not a new procedure
Submit the same work once
Submit one PDF of your completed table and one signal-prediction sentence to Wk4 Data table: Concentration and serial dilution by September 17 at 11:59 PM. If I collected this work on paper, do not upload a second copy. This is 5 points in Daily Work. Do not submit guided notes or a second notebook file.
Wk4 Data table: Concentration and serial dilutionThe calculations predict concentrations under the stated ratios. They do not show what was actually mixed, establish a test result or diagnose a patient. This is a paper-planning task; no samples, reagents or equipment are used.